Tag: TeCA: Tetracyclic Antidepressants

What is Mirtazapine?

Published on by Andrew Marshall1 Comment

Introduction

Mirtazapine, sold under the brand name Remeron among others, is an atypical tetracyclic antidepressant, and as such is used primarily to treat depression. Its effects may take up to four weeks but can also manifest as early as one to two weeks. It is often used in cases of depression complicated by anxiety or insomnia. The effectiveness of mirtazapine is comparable to other commonly prescribed antidepressants. It is taken by mouth.

Common side effects include sleepiness, dizziness, increased appetite and weight gain. Serious side effects may include mania, low white blood cell count, and increased suicide among children. Withdrawal symptoms may occur with stopping. It is not recommended together with a monoamine oxidase inhibitor, although evidence supporting the danger of this combination has been challenged. It is unclear if use during pregnancy is safe. How it works is not clear, but it may involve blocking certain adrenergic and serotonin receptors. Chemically, it is a tetracyclic antidepressant, and is closely related to mianserin. It also has strong antihistaminergic effects.

Mirtazapine came into medical use in the United States in 1996. The patent expired in 2004, and generic versions are available. In 2022, it was the 105th most commonly prescribed medication in the United States, with more than 6 million prescriptions.

Brief History

Mirtazapine was first synthesized at Organon and published in 1989, was first approved for use in major depressive disorder in the Netherlands in 1994, and was introduced in the United States in 1996 under the brand name Remeron.

Medical Uses

Mirtazapine is approved by the United States Food and Drug Administration (FDA) for the treatment of major depressive disorder in adults.

Depression

Mirtazapine is primarily used for major depressive disorder and other mood disorders. Onset of action appears faster than some selective serotonin reuptake inhibitors (SSRIs) and similar to tricyclic antidepressants.

In 2010, the National Institute for Health and Care Excellence recommended generic SSRIs as first-line choices, as they are “equally effective as other antidepressants and have a favourable risk–benefit ratio.” For mirtazapine, it found:

“no difference between mirtazapine and other antidepressants on any efficacy measure, although in terms of achieving remission mirtazapine appears to have a statistical though not clinical advantage. In addition, mirtazapine has a statistical advantage over selective serotonin reuptake inhibitors in terms of reducing symptoms of depression, but the difference is not clinically significant. However, there is strong evidence that patients taking mirtazapine are less likely to leave treatment early because of side effects, although this is not the case for patients reporting side effects or leaving treatment early for any reason.”

A 2011 Cochrane review comparing mirtazapine to other antidepressants found that while it appeared to have a faster onset in people for whom it worked (measured at two weeks), its efficacy was about the same as other antidepressants after six weeks’ use.

A 2012 review focused on antidepressants and sleep found that mirtazapine reduced the time it took to fall asleep and improved the quality of sleep in many people with sleep disorders caused by depression, but that it could also disturb sleep in many people, especially at higher doses, causing restless leg syndrome in 8 to 28% of people and in rare cases causes REM sleep behaviour disorder. This seemingly paradoxical dose–response curve of mirtazapine with respect to somnolence is owed to the exceptionally high affinity of the drug for the histamine H1, 5-HT2A, and 5-HT2C receptors; exhibiting near exclusive occupation of these receptors at doses ≤15 mg. However, at higher doses, inverse agonism and constitutive activation of the α2A-, α2B-, and α2C-adrenergic receptors begins to offset activity at H1 receptors leading to decreased somnolence and even a subjective sensation of “activation” in treated patients.

A 2018 analysis of 21 antidepressants found them to be fairly similar overall. It found tentative evidence for mirtazapine being in the more effective group and middle in tolerability.

After one week of usage, mirtazapine was found to have an earlier onset of action compared to SSRIs.

Other

There is also some evidence supporting its use in treating the following conditions, for which it is sometimes prescribed off-label:

  • Generalised anxiety disorder (GAD)
  • Social anxiety disorder
  • Obsessive–compulsive disorder (OCD)
  • Panic disorder
  • Post-traumatic stress disorder (PTSD)
  • Low appetite/underweight
  • Insomnia
  • Nausea and vomiting
  • Itching
  • Headaches and migraine

Side or Adverse Effects

A 2011 Cochrane review found that, compared with other antidepressants, it is more likely to cause weight gain and sleepiness, but it is less likely to cause tremors than tricyclic antidepressants, and less likely to cause nausea and sexual dysfunction than SSRIs.

Very common (≥10% incidence) adverse effects include constipation, dry mouth, sleepiness, increased appetite (17%) and weight gain (>7% increase in <50% of children).

Common (1–10% incidence) adverse effects include weakness, confusion, dizziness, fasciculations (muscle twitches), peripheral oedema (swelling, usually of the lower limbs), and negative lab results like elevated transaminases, elevated serum triglycerides, and elevated total cholesterol.

Mirtazapine is not considered to have a risk of many of the side effects often associated with other antidepressants like the SSRIs and may improve certain ones when taken in conjunction with them. (Those adverse effects include decreased appetite, weight loss, insomnia, nausea and vomiting, diarrhoea, urinary retention, increased body temperature, excessive sweating, pupil dilation and sexual dysfunction.)

In general, some antidepressants, especially SSRIs, can paradoxically exacerbate some peoples’ depression or anxiety or cause suicidal ideation. Despite its sedating action, mirtazapine is also believed to be capable of this, so in the United States and certain other countries, it carries a black box label warning of these potential effects, especially for people under the age of 25.

Mirtazapine may induce arthralgia (non-inflammatory joint pain).

A case report published in 2000 noted an instance in which mirtazapine counteracted the action of clonidine, causing a dangerous rise in blood pressure.

In a study comparing 32 antidepressants of all pharmacological classes, mirtazapine was one of the antidepressants most likely to cause nightmare disorder, sleepwalking, restless legs syndrome, night terrors and sleep paralysis.

Mirtazapine has been associated with an increased risk of death compared to other antidepressants in several studies. However, it is more likely that the residual differences between people prescribed mirtazapine rather than a SSRI account for the difference in risk of mortality.

Withdrawal

Stopping Mirtazapine and other antidepressants may cause withdrawal symptoms. A gradual and slow reduction in dose is recommended to minimise such symptoms. Effects of sudden cessation of treatment with mirtazapine may include depression, anxiety, tinnitus, panic attacks, vertigo, restlessness, irritability, decreased appetite, insomnia, diarrhoea, nausea, vomiting, flu-like symptoms, allergy-like symptoms such as pruritus, headaches, and sometimes mania or hypomania.

Overdose

Mirtazapine is considered to be relatively safe in the event of an overdose, although it is considered slightly more toxic in overdose than most of the SSRIs (except citalopram). Unlike the tricyclic antidepressants, mirtazapine showed no significant cardiovascular adverse effects at 7 to 22 times the maximum recommended dose.

Twelve reported fatalities have been attributed to mirtazapine overdose. The fatal toxicity index (deaths per million prescriptions) for mirtazapine is 3.1 (95% CI: 0.1 to 17.2). This is similar to that observed with SSRIs.

Interactions

Concurrent use with inhibitors or inducers of the cytochrome P450 isoenzymes CYP1A2, CYP2D6, or CYP3A4 can result in altered concentrations of mirtazapine, as these are the main enzymes responsible for its metabolism. As examples, fluoxetine and paroxetine, inhibitors of these enzymes, are known to modestly increase mirtazapine levels, while carbamazepine, an inducer, considerably decreases them. Liver impairment and moderate chronic kidney disease have been reported to decrease the oral clearance of mirtazapine by about 30%; severe kidney disease decreases it by 50%.

Mirtazapine in combination with a SSRI, serotonin–norepinephrine reuptake inhibitor, or tricyclic antidepressant as an augmentation strategy is considered to be relatively safe and is often employed therapeutically but caution should be given when combined with fluvoxamine. There is a combination of venlafaxine and mirtazapine, sometimes referred to as “California rocket fuel”. Several case reports document serotonin syndrome induced by the combination of mirtazapine with other agents (olanzapine, quetiapine, tramadol and venlafaxine). Adding fluvoxamine to treatment with mirtazapine may cause a significant increase in mirtazapine concentration. This interaction may necessitate an adjustment of the mirtazapine dosage.

According to information from the manufacturers, mirtazapine should not be started within two weeks of any monoamine oxidase inhibitor usage; likewise, monoamine oxidase inhibitors should not be administered within two weeks of discontinuing mirtazapine.

The addition of mirtazapine to a monoamine oxidase inhibitor, while potentially having typical or idiosyncratic (unique to the individual) reactions not herein described, does not appear to cause serotonin syndrome. This is per the fact that the 5-HT2A receptor is the predominant serotonin receptor thought to be involved in the pathophysiology of serotonin syndrome (with the 5-HT1A receptor seeming to be protective). Mirtazapine is a potent 5-HT2A receptor antagonist, and cyproheptadine, a medication that shares this property, mediates recovery from serotonin syndrome and is an antidote against it.

There is a possible interaction that results in a hypertensive crisis when mirtazapine is given to a patient who has already been on steady doses of clonidine. This involves a subtle consideration, when patients have been on chronic therapy with clonidine and suddenly stop the dosing, a rapid hypertensive rebound sometimes (20%) occurs from increased sympathetic outflow. Clonidine’s blood pressure lowering effects are due to stimulation of presynaptic α2 autoreceptors in the CNS which suppress sympathetic outflow. Mirtazapine itself blocks these same α2 autoreceptors, so the effect of adding mirtazapine to a patient stabilised on clonidine may precipitate withdrawal symptoms.

Mirtazapine has been used as a hallucinogen antidote to block the effects of serotonergic psychedelics like psilocybin and lysergic acid diethylamide (LSD).

Pharmacology

Pharmacodynamics

Mirtazapine is sometimes described as a noradrenergic and specific serotonergic antidepressant (NaSSA), although the actual evidence in support of this label has been regarded as poor. It is a tetracyclic piperazine-azepine.

Mirtazapine has antihistamine, α2-blocker, and antiserotonergic activity. It is specifically a potent antagonist or inverse agonist of the α2A-, α2B-, and α2C-adrenergic receptors, the serotonin 5-HT2A, 5-HT2C, and the histamine H1 receptor. Unlike many other antidepressants, it does not inhibit the reuptake of serotonin, norepinephrine, or dopamine, nor does it inhibit monoamine oxidase. Similarly, mirtazapine has weak or no activity as an anticholinergic or blocker of sodium or calcium channels, in contrast to most tricyclic antidepressants. In accordance, it has better tolerability and low toxicity in overdose. As an H1 receptor antagonist, mirtazapine is extremely potent, and is in fact one of the most potent H1 receptor inverse agonists among tricyclic and tetracyclic antidepressants and most antihistamines in general. Antagonism of the H1 receptor is by far the strongest activity of mirtazapine, with the drug acting as a selective H1 receptor antagonist at low concentrations.

The (S)-(+) enantiomer of mirtazapine is responsible for antagonism of the serotonin 5-HT2A and 5-HT2C receptors, while the (R)-(–) enantiomer is responsible for antagonism of the 5-HT3 receptor. Both enantiomers are involved in antagonism of the H1 and α2-adrenergic receptors, although the (S)-(+) enantiomer is the stronger antihistamine.

Although not clinically relevant, mirtazapine has been found to act as a partial agonist of the κ-opioid receptor at high concentrations (EC50 = 7.2 μM).

α2-Adrenergic Receptor

Antagonism of the α2-adrenergic receptors, which function largely as inhibitory autoreceptors and heteroreceptors, enhances adrenergic and serotonergic neurotransmission, notably central 5-HT1A receptor mediated transmission in the dorsal raphe nucleus and hippocampus; hence, mirtazapine’s classification as a NaSSA. Indirect α1 adrenoceptor-mediated enhancement of serotonin cell firing and direct blockade of inhibitory α2 heteroreceptors located on serotonin terminals are held responsible for the increase in extracellular serotonin. Because of this, mirtazapine has been said to be a functional “indirect agonist” of the 5-HT1A receptor. Increased activation of the central 5-HT1A receptor is thought to be a major mediator of efficacy of most antidepressant drugs.

5-HT2 Receptor

Antagonism of the 5-HT2 subfamily of receptors and inverse agonism of the 5-HT2C receptor appears to be in part responsible for mirtazapine’s efficacy in the treatment of depressive states. Mirtazapine increases dopamine release in the prefrontal cortex. Accordingly, it was shown that by blocking the α2-adrenergic receptors and 5-HT2C receptors mirtazapine disinhibited dopamine and norepinephrine activity in these areas in rats. In addition, mirtazapine’s antagonism of 5-HT2A receptors has beneficial effects on anxiety, sleep and appetite, as well as sexual function regarding the latter receptor. Mirtazapine has been shown to lower drug seeking behaviour (more specifically to methamphetamine) in various human and animal studies. It is also being investigated in substance abuse disorders to reduce withdrawal effects and improve remission rates.

Mirtazapine significantly improves pre-existing symptoms of nausea, vomiting, diarrhoea, and irritable bowel syndrome in affected individuals. Mirtazapine may be used as an inexpensive antiemetic alternative to Ondansetron. In conjunction with substance abuse counselling, mirtazapine has been investigated for the purpose of reducing methamphetamine use in dependent individuals with success. In contrast to mirtazapine, the SSRIs, serotonin–norepinephrine reuptake inhibitors, monoamine oxidase inhibitors, and some tricyclic antidepressants acutely increase the general activity of the 5-HT2A, 5-HT2C, and 5-HT3 receptors, leading to a number of negative changes and side effects, the most prominent of which include anorexia, insomnia, nausea, and diarrhoea, among others. However, most of these adverse effects are temporary, since down regulation of 5-HT2A receptors eventually occurs following chronic SSRI treatment, and desensitisation of 5-HT3 receptors often occurs within a week or less. This is precisely why SSRIs have a delayed antidepressant and anxiolytic effect, and occasionally, an acute anxiogenic effect before down regulation occurs. Mirtazapine, on the other hand, is an antagonist of the 5-HT2A receptor, and antagonists at this receptor typically induce reverse tolerance. Thus, the antidepressant and anxiolytic effects of mirtazapine occur more rapidly than with SSRIs. Furthermore, its reduced incidence of sexual dysfunction (such as loss of libido and anorgasmia) could be a product of negligible binding to the serotonin transporter and antagonism of the 5-HT2A receptors; however, Mirtazapine’s high affinity towards and inverse agonism of the 5-HT2C receptors may greatly attenuate those pro-sexual factors (as evidenced by the pro-sexual effects of drugs like m-CPP and lorcaserin which agonise 5-HT2C receptors in a reasonably selective manner). As a result, it is often combined with these drugs to reduce their side-effect profile and to produce a stronger antidepressant effect.

Mirtazapine does not have pro-serotonergic activity and thus does not cause serotonin syndrome. This is in accordance with the fact that it is not a serotonin reuptake inhibitor or monoamine oxidase inhibitor, nor a serotonin receptor agonist. There are no reports of serotonin syndrome in association with mirtazapine alone, and mirtazapine has not been found to cause serotonin syndrome in overdose. However, there are a handful of case reports of serotonin syndrome occurring with mirtazapine in combination with serotonergic drugs like SSRIs, although such reports are very rare, and do not necessarily implicate mirtazapine as causative.

5-HT3 Receptor

(R)-(–)-mirtazapine is a potent 5-HT3 blocker. It may relieve chemotherapy-related and advanced cancer-related nausea.

H1 Receptor

Mirtazapine is a very strong H1 receptor antagonist and, as a result, it can cause powerful sedative and hypnotic effects. A single 15 mg dose of mirtazapine to healthy volunteers has been found to result in over 80% occupancy of the H1 receptor and to induce intense sleepiness. After a short period of chronic treatment, however, the H1 receptor tends to sensitise and the antihistamine effects become more tolerable. Many patients may also dose at night to avoid the effects, and this appears to be an effective strategy for combating them. Blockade of the H1 receptor may improve pre-existing allergies, pruritus, nausea, and insomnia in affected individuals. It may also contribute to weight gain, however. In contrast to the H1 receptor, mirtazapine has only low affinity for the muscarinic acetylcholine receptors, although anticholinergic side effects like dry mouth, constipation, and mydriasis are still sometimes seen in clinical practice.

Pharmacokinetics

The oral bioavailability of mirtazapine is about 50%. It is found mostly bound to plasma proteins, about 85%. It is metabolized primarily in the liver by N-demethylation and hydroxylation via cytochrome P450 enzymes, CYP1A2, CYP2D6, CYP3A4. The overall elimination half-life is 20–40 hours, and this is independent of dosage. It is conjugated in the kidney for excretion in the urine, where 75% of the drug is excreted, and about 15% is eliminated in faeces.  Desmethylmirtazapine is an active metabolite of mirtazapine which is believed to contribute about 3-10% to the drug’s overall effects and has a half-life of about 25 hours.

Chemistry

Mirtazapine is a tetracyclic piperazinoazepine; mianserin was developed by the same team of organic chemists and mirtazapine differs from it via the addition of a nitrogen atom in one of the rings. It is a racemic mixture of enantiomers. The (S)-(+)-enantiomer is known as esmirtazapine.

Analogues of mirtazapine include mianserin, setiptiline, and aptazapine.

Synthesis

A chemical synthesis of mirtazapine has been published. The first step of synthesis is a condensation reaction between the molecule 2-chloro 3-cyanopyridine and the molecule 1-methyl-3-phenylpiperazine.

Society and Culture

Generic Names

Mirtazapine is the English and French generic name of the drug and its INNTooltip International Nonproprietary Name, USANTooltip United States Adopted Name, USPTooltip United States Pharmacopeia, BANTooltip British Approved Name, DCFTooltip Dénomination Commune Française, and JANTooltip Japanese Accepted Name. Its generic name in Spanish, Italian, and Portuguese is mirtazapina and in German, Turkish and Swedish is mirtazapin.

Brand Names

Mirtazapine is marketed under many brand names worldwide, including Adco-Mirteron, Afloyan, Amirel, Arintapin Smelt, Avanza, Axit, Azapin, Beron, Bilanz, Blumirtax, Calixta, Ciblex, Combar, Comenter, Depreram, Divaril, Esprital, Maz, Menelat, Mepirzapine, Merdaten, Meronin, Mi Er Ning, Milivin, Minelza, Minivane, Mirastad, Mirazep, Miro, Miron, Mirrador, Mirt, Mirta, Mirtabene, Mirtadepi, Mirtagamma, Mirtagen, Mirtalan, Mirtamor, Mirtamylan, Mirtan, Mirtaneo, Mirtanza, Mirtapax, Mirtapil, Mirtapine, Mirtaron, Mirtastad, Mirtax, Mirtaz, Mirtazap, Mirtazapin, Mirtazapina, Mirtazapine, Mirtazapinum, Mirtazelon, Mirtazon, Mirtazonal, Mirtel, Mirtimash, Mirtin, Mirtine, Mirtor, Mirzapine, Mirzaten, Mirzest, Mitaprex, Mitaxind, Mitocent, Mitrazin, Mizapin, Motofen, Mytra, Norset, Noxibel, Pharmataz, Promyrtil, Rapizapine, Ramure, Razapina, Redepra, Reflex, Remergil, Remergon, Remeron, Remirta, Rexer, Saxib, Sinmaron, Smilon, Tazepin, Tazimed, Tetrazic, Tifona, U-Mirtaron, U-zepine, Valdren, Vastat, Velorin, Yarocen, Zania, Zapex, Zestat, Zismirt, Zispin, Zuleptan, and Zulin.

Research

The use of mirtazapine has been explored in several additional conditions:

  • Found ineffective for Sleep apnoea/hypopnoea.
  • Secondary symptoms of autistic spectrum conditions and other pervasive developmental disorders.
  • Antipsychotic-induced akathisia.
  • Drug withdrawal, dependence and detoxification.
  • Negative, depressive and cognitive symptoms of schizophrenia (as an adjunct).
  • A case report has been published in which mirtazapine reduced visual hallucinations in a patient with Parkinson’s disease psychosis (PDP). This is in alignment with recent findings that inverse agonists at the 5-HT2A receptors are efficacious in attenuating the symptoms of Parkinson’s disease psychosis. As is supported by the common practice of prescribing low-dose quetiapine and clozapine for PDP at doses too low to antagonise the D2 receptor, but sufficiently high doses to inversely agonise the 5-HT2A receptors.
  • Eight case reports have been reported in five papers on the use of mirtazapine in the treatment of hives as of 2017.
  • Mirtazapine to alleviate severe breathlessness in patients with COPD or interstitial lung diseases (BETTER-B). Found ineffective and potentially harmful.

Veterinary Use

Mirtazapine also has some veterinary use in cats and dogs. Mirtazapine is sometimes prescribed as an appetite stimulant for cats or dogs experiencing loss of appetite due to medical conditions such as chronic kidney disease. It is especially useful for treating combined poor appetite and nausea in cats and dogs.

Mirtazapine is indicated for bodyweight gain in cats experiencing poor appetite and weight loss resulting from chronic medical conditions.

There are two options for administration: tablets given orally, and an ointment applied topically to the inner surface of the ear.

The most common side effects include signs of local irritation or inflammation at the site where the ointment is applied and behavioural changes (increased meowing, hyperactivity, disoriented state or inability to coordinate muscle movements, lack of energy/weakness, attention-seeking, and aggression).

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What is Setiptiline?

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Introduction

Setiptiline (brand name Tecipul), also known as teciptiline, is a tetracyclic antidepressant (TeCA) that acts as a noradrenergic and specific serotonergic antidepressant (NaSSA). It was launched in 1989 for the treatment of depression in Japan by Mochida.

Pharmacology

Pharmacodynamics

Setiptiline acts as a norepinephrine reuptake inhibitor, α2-adrenergic receptor antagonist, and serotonin receptor antagonist, likely at the 5-HT2 subtypes, as well as an H1 receptor inverse agonist/antihistamine.

Chemistry

Setiptiline has a tetracyclic structure and is a close analogue of mianserin and mirtazapine, with setiptiline being delta(13b,4a),4a-carba-mianserin, and mirtazapine being 6-azamianserin.

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What is Esmirtazapine?

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Introduction

Esmirtazapine (ORG-50,081) is a tetracyclic antidepressant drug which was under development by Organon for the treatment of insomnia and vasomotor symptoms (e.g. hot flashes) associated with menopause.

Outline

Esmirtazapine is the (S)-(+)-enantiomer of mirtazapine and possesses similar overall pharmacology, including inverse agonist actions at H1 and 5-HT2 receptors and antagonist actions at α2-adrenergic receptors.

Notably, esmirtazapine has a shorter half life of around 10 hours, compared to R-mirtazapine and racemic mixture, which has a half-life of 18-40 hours. Merck has run several studies on low dose (3 – 4.5 mg) esmirtazapine for the treatment of insomnia. It is attractive for treating insomnia since it is a potent H1-inhibitor and a 5-HT2A antagonist. Unlike low-dose mirtazapine, the half life (10 hours) is short enough that next-day sedation may be manageable, however, for people with CYP2D6 polymorphisms, which constitute a sizable fraction of the population, the half-life is expected to be quite a bit longer. Merck researchers claimed that the incidence of next-day sedation was not a problem in one of their studies, but this claim has been challenged (15% of patients complained of daytime sleepiness vs 3.5% in the placebo group).

In March 2010, Merck terminated its internal clinical development programme for esmirtazapine for hot flashes and insomnia, “for strategic reasons”.

This page is based on the copyrighted Wikipedia article < https://en.wikipedia.org/wiki/Esmirtazapine >; it is used under the Creative Commons Attribution-ShareAlike 3.0 Unported License (CC-BY-SA). You may redistribute it, verbatim or modified, providing that you comply with the terms of the CC-BY-SA.

What is Aptazapine?

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Introduction

Aptazapine (developmental code name CGS-7525A) is a tetracyclic antidepressant (TeCA) that was assayed in clinical trials for the treatment of depression in the 1980s but was never marketed.

Outline

It is a potent α2-adrenergic receptor antagonist with ~10x the strength of the related compound mianserin and has also been shown to act as a 5-HT2 receptor antagonist and H1 receptor inverse agonist, while having no significant effects on the reuptake of serotonin or norepinephrine.

Based on its pharmacological profile, aptazapine may be classified as a noradrenergic and specific serotonergic antidepressant (NaSSA).

This page is based on the copyrighted Wikipedia article < https://en.wikipedia.org/wiki/Aptazapine >; it is used under the Creative Commons Attribution-ShareAlike 3.0 Unported License (CC-BY-SA). You may redistribute it, verbatim or modified, providing that you comply with the terms of the CC-BY-SA.

What is an Atypical Antidepressant?

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Introduction

An atypical antidepressant is any antidepressant medication that acts in a manner that is different from that of most other antidepressants.

Refer to Second-Generation Antidepressant, Tricyclic Antidepressant, and Tetracyclic Antidepressant.

Background

Atypical antidepressants include agomelatine, bupropion, mianserin, mirtazapine, nefazodone, opipramol, tianeptine, and trazodone. The agents vilazodone and vortioxetine are partly atypical. Typical antidepressants include the SSRIs, SNRIs, TCAs, and MAOIs, which act mainly by increasing the levels of the monoamine neurotransmitters serotonin and/or norepinephrine. Among TCAs, trimipramine is an atypical agent in that it appears not to do this. In August 2020, Esketamine (JNJ-54135419) was approved by the US Food and Drug Administration (FDA) for the treatment for treatment-resistant depression with the added indication for the short-term treatment of suicidal thoughts.

Buprenorphine/Samidorphan (ALKS-5461) is an antidepressant with a novel mechanism of action which is under development and is considered an atypical antidepressant. They act faster than available antidepressants.

What is a Second-Generation Antidepressant?

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Introduction

The second-generation antidepressants are a class of antidepressants characterised primarily by the era of their introduction, approximately coinciding with the 1970s and 1980s, rather than by their chemical structure or by their pharmacological effect. As a consequence, there is some controversy over which treatments actually belong in this class.

Refer to Atypical Antidepressant, Tricyclic Antidepressant, and Tetracyclic Antidepressant.

The term “third generation antidepressant” is sometimes used to refer to newer antidepressants, from the 1990s and 2000s, often selective serotonin reuptake inhibitors (SSRIs) such as; fluoxetine (Prozac), paroxetine (Paxil) and sertraline (Zoloft), as well as some non-SSRI antidepressants such as mirtazapine, nefazodone, venlafaxine, duloxetine and reboxetine. However, this usage is not universal.

Examples

This list is not exhaustive, and different sources vary upon which items should be considered second-generation.

  • Amineptine.
  • Amoxapine.
  • Bupropion.
  • Iprindole.
  • Maprotiline.
  • Medifoxamine.
  • Mianserin.
  • Nomifensine.
  • Tianeptine.
  • Trazodone.
  • Venlafaxine.
  • Viloxazine.

What is Maprotiline?

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Introduction

Maprotiline, sold under the brand name Ludiomil among others, is a tetracyclic antidepressant (TeCA) that is used in the treatment of depression.

It may alternatively be classified as a tricyclic antidepressant (TCA), specifically a secondary amine. In terms of its chemistry and pharmacology, maprotiline is closely related to other secondary amine TCAs like nortriptyline and protriptyline, and has similar effects to them.

Brief History

Maprotiline was developed by Ciba (now operated by Novartis). It was patented in 1966 and was first described in the literature in 1969. The drug was introduced for medical use in 1974. Generics are now widely available. It was introduced after most of the other TCAs but was the first TeCA to be developed and marketed, with the TeCAs mianserin and amoxapine following shortly thereafter and mirtazapine being introduced later on.

Medical Uses

Maprotiline is used in the treatment of depression, such as depression associated with agitation or anxiety and has similar efficacy to the antidepressant drug moclobemide.

  • Treatment of depression of all forms and severities (endogenous, psychotic, involutional, and neurotic) especially for depression associated with agitation or anxiety.
  • Panic disorder.
  • Neuropathic pain.
  • Treatment of the depressive phase in bipolar depression.
  • For the symptomatic relief of anxiety, tension or insomnia.

The use of maprotiline in the treatment of enuresis in paediatric patients has so far not been systematically explored and its use is not recommended. Safety and effectiveness in the paediatric population in general have not been established. Anyone considering the use of maprotiline in a child or adolescent must balance the potential risks with the clinical need. In general, lower dosages are recommended for patients over 60 years of age. Dosages of 50 mg to 75 mg daily are usually satisfactory as maintenance therapy for elderly patients who do not tolerate higher amounts.[8][9]

Available Forms

  • Coated Tablets, 10 mg, 25 mg, 50 mg, and 75 mg.
  • Injectable concentrate, 25 mg.

Contraindications

Maprotiline may worsen psychotic conditions like schizophrenia and should be given with caution. The antipsychotic treatment should be continued. Patients with bipolar affective disorder should not receive antidepressants whilst in a manic phase, as antidepressants can worsen mania.

Absolute

  • Hypersensitivity to maprotiline or to other TCAs and TeCAs.
  • Hypertrophy of the prostate gland with urine hesitancy.
  • Closed angle glaucoma.

Special Caution Needed

  • Concomitant treatment with a MAO inhibitor.
  • Serious impairment of liver and kidney function.
  • Epilepsy and other conditions that lower the seizure threshold (active brain tumours, alcohol withdrawal, other medications).
  • Serious cardiovascular conditions (arrhythmias, heart insufficience, state after myocardial infarction etc.).
  • Treatment of patients under age 18.

Suicidal Patients

Same as other antidepressants, maprotiline increased the risk compared to placebo of suicidal thinking and behaviour (suicidality) in children, adolescents and young adults in short-term studies of major depressive disorder (MDD) and other psychiatric disorders. Anyone considering the use of maprotiline or any other antidepressant in a child, adolescent, or young adult must balance this risk with the clinical need. Short-term studies did not show an increase in the risk of suicidality with antidepressants compared to placebo in adults beyond age 24; there was a reduction in risk with antidepressants compared to placebo in adults aged 65 and older. Depression and certain other psychiatric disorders are themselves associated with increases in the risk of suicide. Patients of all ages who are started on antidepressant therapy should be monitored appropriately and observed closely for clinical worsening, suicidality, or unusual changes in behaviour. Families and caregivers should be advised of the need for close observation and communication with the prescriber. Maprotiline is not approved for use in paediatric patients.

Pregnancy and Lactation

Reproduction studies have been performed in female laboratory rabbits, mice, and rats at doses up to 1.3, 7, and 9 times the maximum daily human dose respectively and have revealed no evidence of impaired fertility or harm to the foetus due to maprotiline. There are, however, no adequate and well controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

Maprotiline is excreted in breast milk. At steady-state, the concentrations in milk correspond closely to the concentrations in whole blood. Caution should be exercised when maprotiline hydrochloride is administered to a nursing woman.

Side Effects

The side-effect profile is comparable to other TCAs and TeCAS and many of the following are due to anticholinergic (which are less prominent than those of most TCAs) and antihistamine effects. Most often seen are:

  • Dizziness.
  • Drowsiness.
  • Somnolence.
  • Fatigue.
  • Dry mouth (and complications of long-term uncontrolled dry mouth such as dental caries).
  • Constipation.
  • Vertigo.
  • Nausea (rare, incidence of ~2%) and vomiting.
  • Increased appetite and weight gain.
  • Orthostatic hypotension, hypertension, sinus tachycardia, heart-block, arrhythmias and other cardiac effects.
  • Sexual dysfunction in men: impotence, priapism, delayed ejaculation, anejaculation, decreased libido.
  • Sexual dysfunction in women: decreased libido, vaginal dryness, painful sexual intercourse, anorgasmia.
  • Allergic skin reactions such as rash or urticaria (more often than with other antidepressants).
    • Rarely, severe skin reactions such as erythema multiforme can occur.
  • Photosensitivity.
  • Agitation, confusion.
  • Induction of hypomania or mania in patients suffering from underlying bipolar affective disorder.
  • Psychotic symptoms.
  • Tremor.
  • Extrapyramidal symptoms.
  • Headache.
  • Seizures (at high doses).
  • Rare haematological complications: leukopenia and agranulocytosis (dangerous fall in white blood cells).
  • Fever.
  • Urinary retention.

Maprotiline causes a strong initial sedation (first 2 to 3 weeks of therapy) and is therefore indicated to treat agitated patients or those with suicidal risks. It causes anticholinergic side effects (dry mouth, constipation, confusion, tachycardia) with a lower incidence than amitriptyline. Originally, the manufacturer claimed that maprotiline is better tolerated than other TCAs and TeCAs. However, seizures, leukopenia and skin reactions occur more often with maprotiline than with comparable drugs like amitriptyline.

Maprotiline has no known potential for abuse and psychological dependence.

Withdrawal

Withdrawal symptoms frequently seen when treatment with maprotiline is stopped abruptly (agitation, anxiety, insomnia, sometimes activation of mania or rebound depression) are not indicative of addiction and can be avoided by reducing the daily dose of maprotiline gradually by approximately 25% each week. If treatment has to be stopped at once due to medical reasons, the use of a benzodiazepine (e.g. lorazepam, clonazepam, or alprazolam) for a maximum of 4 weeks as needed will usually suppress withdrawal symptoms.

Interactions

Maprotiline has a wide range of possible interactions. Some are typical for TCAs and TeCAs, others are caused by specific metabolic effects (e.g. high plasma-protein-binding) of maprotiline:

  • Irreversible MAO-inhibitors: agitation, delirium, coma, hyperpyrexia (high fever), seizures and severe changes in blood pressure.
  • Treatment-resistant and hospitalised patients may be treated concomitantly with an MAO-inhibitor, if they are closely monitored and if the initial dose of the MAO-Inhibitor is low.

Increased Drug Actions

  • Other antidepressants, barbiturates, narcotics, sedating antihistamines, anticonvulsive drugs, alcohol, resulting in increased central depression.
  • Anticholinergics (antiparkinsonian agents, TCAs and TeCAs) – resulting in increased anticholinergic action (dry mouth, constipation etc.).
  • Sympathomimetics (also those used in local anaesthetics like noradrenaline):
    • Sympathomimetic effects increased (increased blood pressure, pulse rate, paleness of skin etc.)
  • Nitrates and anti-hypertensives (e.g. beta-blockers), increased antihypertensive action with pronounced fall in blood pressure.

Decreased Drug Actions

  • Guanethidine, Reserpine, Guanfacine : antihypertensive effects decreased.
  • Clonidine: antihypertensive effects decreased and risk of (massive) rebound hypertension.

Other Types of Interaction

  • Drugs, which induce certain enzymes in the liver, e.g. barbiturates, phenytoin, carbamazepine and oral anti-conceptive drugs, enhance the elimination of maprotiline and decrease its antidepressant effects.
    • Additionally the blood-concentrations of phenytoin or carbamazepine may be increased, leading to a higher incidents of side effects.
  • The concomitant use of maprotiline and neuroleptics can lead to increased maprotiline blood-levels and to seizures.
    • Combining maprotiline and thioridazine could induce severe arrhythmias.
  • Additionally, increased blood-levels of Maprotiline are possible, if certain beta-blocking agents (e.g. Propranolol) are given concomitantly.
  • Maprotiline may amplify the actions of coumarin-type anticoagulants (e.g. warfarin, phenprocoumon).
    • The plasma-prothrombin-activity must be assessed closely in order to avoid overt bleedings.
  • Maprotiline can increase the actions of oral antidiabetic drugs (sulfonylureas) and Insulin.
    • Diabetic patients should have regular assessments of their blood-glucose-levels.
  • The concomitant application with fluoxetine or fluvoxamine may lead to significantly increased plasma-levels of maprotiline with a high incidence of maprotiline side effects.
    • Due to the long half-lives of fluoxetine and fluvoxamine this effect may persist.

Pharmacology

Pharmacodynamics

Maprotiline exhibits strong effects as a norepinephrine reuptake inhibitor with only weak actions the reuptake of serotonin and dopamine. It is also a strong antagonist of the H1 receptor, a moderate antagonist of the 5-HT2 and α1-adrenergic receptors, and a weak antagonist of the D2 and muscarinic acetylcholine receptors. Maprotiline has also more recently been identified as a potent antagonist of the 5-HT7 receptor, with this action potentially playing an important role in its antidepressant effectiveness. The drug is a strong antihistamine, but unlike most TCAs, has minimal anticholinergic effects.

The pharmacological profile of maprotiline explains its antidepressant, sedative, anxiolytic, and sympathomimetic activities. In accordance to the pharmacological characteristics it is used in the treatment of depression, such as depression associated with agitation or anxiety. Additionally, it shows strong antagonism against reserpine-induced effects in animal studies, as do the other ‘classical’ antidepressants. Although maprotiline behaves in most regards as a ‘first-generation antidepressant’ it is commonly referred to as ‘second-generation antidepressant’.

The postulated mechanism of maprotiline is that it acts primarily by potentiation of central adrenergic synapses by blocking reuptake of norepinephrine at nerve endings. This pharmacological action is thought to be primarily responsible for the drug’s antidepressant and anxiolytic effects. It is a strong norepinephrine reuptake inhibitor with only weak effects on serotonin and dopamine reuptake. At higher doses however, maprotiline increases serotonergic transmission and increases the level of serotonin available.

Pharmacokinetics

After oral use absorption is good. It binds to plasma proteins 80-90%. Maximal plasma concentration is reached 6 hours after use. The mean time to peak is 12 hours. The terminal half-life of averages 51 hours.

Chemistry

Maprotiline is a tetracyclic compound and is grouped with the TeCAs. Its chemical name is N-methyl-9,10-ethanoanthracen-9(10H)-propylamine. The drug has a dibenzobicyclo[2.2.2]octadiene (9,10-dihydro-9,10-ethanoanthracene) ring system; that is, a tricyclic anthracene ring system with an ethylene bridge across the central ring. This results in it having a unique three-dimensional central ring (a bicyclo[2.2.2]octane or 1,4-endoethylenecyclohexane ring) and being a tetracyclic rather than a tricyclic compound. However, it could also or alternatively be considered to be a tricyclic and hence a TCA. In addition to its heterocyclic ring system, maprotiline has an alkylamine side chain attached similarly to other TCAs (but notably unlike other TeCAs). In terms of the side chain, it is a secondary amine, and its chemical structure, aside from the ethylene link in the central ring, is similar to that of secondary amine TCAs like nortriptyline and protriptyline. In accordance, the pharmacology of maprotiline is very similar to that of secondary amine TCAs.

Maprotiline is very similar in structure to the anxiolytic, sedative, and muscle relaxant drug benzoctamine (Tacitin). The only structural difference between the two compounds is in the length of their side chain. However, this modification results in considerable differences in their pharmacological and therapeutic effects.

Society and Culture

Generic Names

Maprotiline is the English and French generic name of the drug and its INN, USAN, BAN, and DCF, while maprotiline hydrochloride is its USAN, USP, BANM and JAN. Its generic name in Spanish and Italian and its DCIT are maprotilina, in German is maprotilin, and in Latin is maprotilinum. The methanesulfonate (mesylate) salt is known unofficially as maprotiline methanesulfonate.

Brand Names

Maprotiline is marketed throughout the world mainly under the brand name Ludiomil. It is also available under a variety of other brand names including Deprilept, Maprolu, and Psymion among others.

What is the Management of Depression?

Published on by Andrew MarshallLeave a comment

Introduction

Depression is a symptom of some physical diseases; a side effect of some drugs and medical treatments; and a symptom of some mood disorders such as major depressive disorder or dysthymia. Physical causes are ruled out with a clinical assessment of depression that measures vitamins, minerals, electrolytes, and hormones. Management of depression may involve a number of different therapies: medications, behaviour therapy, psychotherapy, and medical devices.

Though psychiatric medication is the most frequently prescribed therapy for major depression, psychotherapy may be effective, either alone or in combination with medication. Combining psychotherapy and antidepressants may provide a “slight advantage”, but antidepressants alone or psychotherapy alone are not significantly different from other treatments, or “active intervention controls”. Given an accurate diagnosis of major depressive disorder, in general the type of treatment (psychotherapy and/or antidepressants, alternate or other treatments, or active intervention) is “less important than getting depressed patients involved in an active therapeutic program.”

Psychotherapy is the treatment of choice in those under the age of 18, with medication offered only in conjunction with the former and generally not as a first line agent. The possibility of depression, substance misuse or other mental health problems in the parents should be considered and, if present and if it may help the child, the parent should be treated in parallel with the child.

Psychotherapy and Behaviour Therapy

There are a number of different psychotherapies for depression which are provided to individuals or groups by psychotherapists, psychiatrists, psychologists, clinical social workers, counsellors or psychiatric nurses. With more chronic forms of depression, the most effective treatment is often considered to be a combination of medication and psychotherapy. Psychotherapy is the treatment of choice in people under 18. A meta-analysis examined the effectiveness of psychotherapy for depression across ages from younger than 13 years to older than 75 years. It summarizes results from 366 trials included 36,702 patients. It found that the best results were for young adults, with an average effect size of g=.98 (95% CI, 0.79-1.16). The effects were smallest for young children (<13 years), g = .35 (95% CI, 0.15-0.55), and second largest in the oldest group, g = .97 (95% CI, 0.42-1.52). The study was not able to compare the different types of therapy to each other. Most of the studies with children used therapies originally developed with adults, which may have reduced the effectiveness. The greater benefits with young adults might be due to a large number of studies including college students, who might have an easier time learning therapy skills and techniques. Most of the studies in children were done in the USA, whereas in older age groups, more balanced numbers of studies came from Europe and other parts of the world as well.

As the most studied form of psychotherapy for depression, cognitive behavioural therapy (CBT) is thought to work by teaching clients to learn a set of cognitive and behavioural skills, which they can employ on their own. Earlier research suggested that cognitive behavioural therapy was not as effective as antidepressant medication in the treatment of depression; however, more recent research suggests that it can perform as well as antidepressants in treating patients with moderate to severe depression. Beck’s treatment manual, Cognitive therapy of depression, has undergone the most research and accumulated the most evidence for its use. However, a number of other CBT manuals also have evidence to support their effectiveness with depression.

The effect of psychotherapy on patient and clinician rated improvement as well as on revision rates have declined steadily from the 1970s.

A systematic review of data comparing low-intensity CBT (such as guided self-help by means of written materials and limited professional support, and website-based interventions) with usual care found that patients who initially had more severe depression benefited from low-intensity interventions at least as much as less-depressed patients.

For the treatment of adolescent depression, one published study found that CBT without medication performed no better than a placebo, and significantly worse than the antidepressant fluoxetine. However, the same article reported that CBT and fluoxetine outperformed treatment with only fluoxetine. Combining fluoxetine with CBT appeared to bring no additional benefit in two different studies or, at the most, only marginal benefit, in a fourth study.

Behaviour therapy for depression is sometimes referred to as behavioural activation. Studies exist showing behavioural activation to be superior to CBT. In addition, behavioural activation appears to take less time and lead to longer lasting change. Two well-researched treatment manuals include Social skills training for depression and Behavioural activation treatment for depression.

Emotionally focused therapy, founded by Sue Johnson and Les Greenberg in 1985, treats depression by identifying and processing underlying emotions. The treatment manual, Facilitating emotional change, outlines treatment techniques.

Acceptance and commitment therapy (ACT), a mindfulness form of CBT, which has its roots in behaviour analysis, also demonstrates that it is effective in treating depression, and can be more helpful than traditional CBT, especially where depression is accompanied by anxiety and where it is resistant to traditional CBT.

A review of four studies on the effectiveness of mindfulness-based cognitive therapy (MBCT), a recently developed class-based program designed to prevent relapse, suggests that MBCT may have an additive effect when provided with the usual care in patients who have had three or more depressive episodes, although the usual care did not include antidepressant treatment or any psychotherapy, and the improvement observed may have reflected non-specific or placebo effects. Of note, although Mindfulness-based cognitive therapy for depression prevented relapse of future depressive episodes, there is no research on whether it can cause the remission of a current depressive episode.

Interpersonal psychotherapy (IPT) focuses on the social and interpersonal triggers that may cause depression. There is evidence that it is an effective treatment for depression. Here, the therapy takes a fairly structured course (often 12 sessions, as in the original research versions) as in the case with CBT; however, the focus is on relationships with others. Unlike family therapy, IPT is an individual format, so it is possible to work on interpersonal themes even if other family members do not come to the session. Therapy can be used to help a person develop or improve interpersonal skills in order to allow him or her to communicate more effectively and reduce stress. In a meta-analysis of 16 studies and 4,356 patients, the average improvement in depressive symptoms was an effect size of d = 0.63 (95% CI, 0.36 to 0.90). IPT combined with pharmacotherapy was more effective in preventing relapse than pharmacotherapy alone, number needed to treat = 7.63.

Psychoanalysis, a school of thought founded by Sigmund Freud that emphasizes the resolution of unconscious mental conflicts, is used by its practitioners to treat clients presenting with major depression. A more widely practiced technique, called psychodynamic psychotherapy, is loosely based on psychoanalysis and has an additional social and interpersonal focus. In a meta-analysis of three controlled trials, psychodynamic psychotherapy was found to be as effective as medication for mild to moderate depression.

Shared Care

Shared decision making is an approach whereby patients and clinicians freely share important evidence when tasked with decision making and where patients are guided to consider the best available options to make an informed decision. The principles are well documented, but there is a gap in that it’s hard to apply them in routine clinical practice. The steps have been simplified into five steps. The first step is seeking patient participation in that the health practitioner is tasked with communicating existing choices and therefore inviting them to the decision making process. The next step involves assisting the patient to explore and compare the treatment options by a critical analysis of the risks and benefits. The third step involves the assessment of the patient’s values and what they prefer taking to account what is of paramount urgency to the patient. Step 4 involves decision making where the patient and the practitioner make a conclusive decision on the best option and arrange for subsequent follow up meetings. Finally, the fifth step involves the analysis of the patient’s decision’. Five steps for you and your patients to work together to make the best possible health care decisions. The step involves monitoring of the degree of implementation, overcoming of barriers of decision implantation consequently the decisions need to be revisited and optimised thus ensuring the decision has a positive impact on health outcomes its success relies on the ability of the health practitioner to create a good interpersonal relationship with the patient.

Depression still remains a major problem in the US whereby statistics have it that 16 million people were affected in the year 2017. The depression is multifactorial and has been on the increase due to societal pressure, genetic association and increase in use of drugs. incorporation of nursing in management of depression may seem important in that nursing holds a pivotal role in health care delivery where they are the health practitioners that have been trained to be versatile from clinical to psychological care. Their incorporation in shared decision making in treating depression may be important as nurses are known to have the best interpersonal relationship with the patients thus a better collaborative model can be achieved due to this fact. With this in mind, the nurses may serve to administer drugs in management, prepare and maintain the patient’s records, interaction with other care staff to achieve optimum care, and organising therapy sessions. In a study another study concerning shared decision-making interventions for people with mental health conditions there were no overt benefits that were discovered and the called for further research in this area. Another study found that it is important to begin the dissemination and implementation of SDM as they proved that it has benefits in healthcare especially in mental health care and has received social and government support and however transitioning to SDM has proven to be an uphill task. It has been suggested that SDM is of importance in demonstrating patient preferences in decision making when there is no clear approach to treatment. In addition, numerous tools can be used to make the decision making the process easier these include the Controlled Preferences Scale that informs clinicians on how to actively involve patients

Commentators suggest that providers need to embrace shared decision making by making sure that patients participate actively in their management thus enabling the success of the model.

Medication

To find the most effective pharmaceutical drug treatment, the dosages of medications must often be adjusted, different combinations of antidepressants tried, or antidepressants changed. Norepinephrine reuptake inhibitor (NRIs) can be used as antidepressants. Selective serotonin reuptake inhibitors (SSRIs), such as sertraline (Zoloft, Lustral), escitalopram (Lexapro, Cipralex), fluoxetine (Prozac), paroxetine (Seroxat), and citalopram, are the primary medications considered, due to their relatively mild side effects and broad effect on the symptoms of depression and anxiety, as well as reduced risk in overdose, compared to their older tricyclic alternatives. Those who do not respond to the first SSRI tried can be switched to another. If sexual dysfunction is present prior to the onset of depression, SSRIs should be avoided. Another popular option is to switch to the atypical antidepressant bupropion (Wellbutrin) or to add bupropion to the existing therapy; this strategy is possibly more effective. It is not uncommon for SSRIs to cause or worsen insomnia; the sedating noradrenergic and specific serotonergic antidepressant (NaSSA) antidepressant mirtazapine (Zispin, Remeron) can be used in such cases. CBT for Insomnia can also help to alleviate the insomnia without additional medication. Venlafaxine (Effexor) from the SNRI class may be moderately more effective than SSRIs; however, it is not recommended as a first-line treatment because of the higher rate of side effects, and its use is specifically discouraged in children and adolescents. Fluoxetine is the only antidepressant recommended for people under the age of 18, though, if a child or adolescent patient is intolerant to fluoxetine, another SSRI may be considered. Evidence of effectiveness of SSRIs in those with depression complicated by dementia is lacking.

Tricyclic antidepressants (TCAs) have more side effects than SSRIs (but less sexual dysfunctions) and are usually reserved for the treatment of inpatients, for whom the tricyclic antidepressant amitriptyline, in particular, appears to be more effective. A different class of antidepressants, the monoamine oxidase inhibitors, have historically been plagued by questionable efficacy (although early studies used dosages now considered too low) and life-threatening adverse effects. They are still used only rarely, although newer agents of this class (RIMA), with a better side effect profile, have been developed.

In older patients TCAs and SSRIs are of the same efficacy. However, there are differences between TCA related antidepressants and classical TCAs in terms of side effect profiles and withdrawal when compared to SSRIs.

There is evidence a prominent side-effect of antidepressants, emotional blunting, is confused with a symptom of depression itself. The cited study, according to Professor Linda Gask was: ‘funded by a pharmaceutical company (Servier) and two of its authors are employees of that company’, which may bias the results. The study authors’ note: “emotional blunting is reported by nearly half of depressed patients on antidepressants and that it appears to be common to all monoaminergic antidepressants not only SSRIs”. Additionally, they note: “The OQuESA scores are highly correlated with the HAD depression score; emotional blunting cannot be described simply as a side-effect of antidepressant, but also as a symptom of depression…More emotional blunting is associated with a poorer quality of remission…”

Acetyl-l-Carnitine

Acetylcarnitine levels were lower in depressed patients than controls and in rats it causes rapid antidepressant effects through epigenetic mechanisms. A systematic review and meta-analysis of 12 randomised controlled trials found “supplementation significantly decreases depressive symptoms compared with placebo/no intervention, while offering a comparable effect with that of established antidepressant agents with fewer adverse effects.”

Zinc

A 2012 cross-sectional study found an association between zinc deficiency and depressive symptoms among women, but not men, and a 2013 meta-analysis of 17 observational studies found that blood zinc concentrations were lower in depressed subjects than in control subjects. A 2012 meta-analysis found that zinc supplementation as an adjunct to antidepressant drug treatment significantly lowered depressive symptom scores of depressed patients. The potential mechanisms underlying the association between low serum zinc and depression remain unclear, but may involve the regulation of neurotransmitter, endocrine and neurogenesis pathways. Zinc supplementation has been reported to improve symptoms of ADHD and depression. A 2013 review found that zinc supplementation may be an effective treatment in major depression.

Magnesium

Many studies have found an association between magnesium intake and depression. Magnesium was lower in serum of depressed patients than controls. One trial found magnesium chloride to be effective for depression in seniors with type 2 diabetes while another trial found magnesium citrate decreased depression in patients with fibromyalgia. One negative trial used magnesium oxide, which is poorly absorbed. A randomised, open-label study found that consumption of magnesium chloride for 6 weeks resulted in a clinically significant net improvement in depression, and that effects were observed within 2 weeks.

Augmentation

Physicians often add a medication with a different mode of action to bolster the effect of an antidepressant in cases of treatment resistance; a 2002 large community study of 244,859 depressed Veterans Administration patients found that 22% had received a second agent, most commonly a second antidepressant. Lithium has been used to augment antidepressant therapy in those who have failed to respond to antidepressants alone. Furthermore, lithium dramatically decreases the suicide risk in recurrent depression. Addition of atypical antipsychotics when the patient has not responded to an antidepressant is also known to increase the effectiveness of antidepressant drugs, albeit at the cost of more frequent and potentially serious side effects. There is some evidence for the addition of a thyroid hormone, triiodothyronine, in patients with normal thyroid function. Stephen M. Stahl, renowned academician in psychopharmacology, has stated resorting to a dynamic psychostimulant, in particular, d-amphetamine is the “classical augmentation strategy for treatment-refractory depression”. However, the use of stimulants in cases of treatment-resistant depression is relatively controversial.

Efficacy of Medication and Psychotherapy

Antidepressants are statistically superior to placebo but their overall effect is low-to-moderate. In that respect they often did not exceed the National Institute for Health and Clinical Excellence (NICE) criteria for a “clinically significant” effect. In particular, the effect size was very small for moderate depression but increased with severity, reaching “clinical significance” for very severe depression. These results were consistent with the earlier clinical studies in which only patients with severe depression benefited from either psychotherapy or treatment with an antidepressant, imipramine, more than from the placebo treatment. Despite obtaining similar results, the authors argued about their interpretation. One author concluded that there “seems little evidence to support the prescription of antidepressant medication to any but the most severely depressed patients, unless alternative treatments have failed to provide benefit.” The other author agreed that “antidepressant ‘glass’ is far from full” but disagreed “that it is completely empty”. He pointed out that the first-line alternative to medication is psychotherapy, which does not have superior efficacy.

Antidepressants in general are as effective as psychotherapy for major depression, and this conclusion holds true for both severe and mild forms of MDD. In contrast, medication gives better results for dysthymia. The subgroup of SSRIs may be slightly more efficacious than psychotherapy. On the other hand, significantly more patients drop off from the antidepressant treatment than from psychotherapy, likely because of the side effects of antidepressants. Successful psychotherapy appears to prevent the recurrence of depression even after it has been terminated or replaced by occasional “booster” sessions. The same degree of prevention can be achieved by continuing antidepressant treatment.

Two studies suggest that the combination of psychotherapy and medication is the most effective way to treat depression in adolescents. Both TADS (Treatment of Adolescents with Depression Study) and TORDIA (Treatment of Resistant Depression in Adolescents) showed very similar results. TADS resulted in 71% of their teen subjects having “much” or “very much” improvement in mood over the 61% with medication alone and 43% with CBT alone. Similarly, TORDIA showed a 55% improvement with CBT and drugs versus a 41% with drug therapy alone. However, a more recent meta-analysis of 34 trials of 14 drugs used with children and adolescents found that only fluoxetine produced significant benefit compared to placebo, with a medium sized effect (standardize mean difference = .5).

Treatment Resistance

The risk factors for treatment resistant depression are: the duration of the episode of depression, severity of the episode, if bipolar, lack of improvement in symptoms within the first couple of treatment weeks, anxious or avoidant and borderline comorbidity and old age. Treatment resistant depression is best handled with a combination of conventional antidepressant together with atypical antipsychotics. Another approach is to try different antidepressants. It is inconclusive which approach is superior. Treatment resistant depression can be misdiagnosed if subtherapeutic doses of antidepressants is the case, patient nonadherence, intolerable adverse effects or their thyroid disease or other conditions is misdiagnosed as depression.

Experimental Treatments

Chromium

Clinical and experimental studies have reported antidepressant activity of chromium particularly in atypical depression, characterised by increased appetite and carbohydrate craving.

Essential Fatty Acids

A 2015 Cochrane Collaboration review found insufficient evidence with which to determine if omega-3 fatty acid has any effect on depression. A 2016 review found that if trials with formulations containing mostly eicosapentaenoic acid (EPA) are separated from trials using formulations containing docosahexaenoic acid (DHA), it appeared that EPA may have an effect while DHA may not, but there was insufficient evidence to be sure.

Creatine

The amino acid creatine, commonly used as a supplement to improve the performance of bodybuilders, has been studied for its potential antidepressant properties. A double-blinded, placebo-controlled trial focusing on women with major depressive disorder found that daily creatine supplementation adjunctive to escitalopram was more effective than escitalopram alone. Studies on mice have found that the antidepressant effects of creatine can be blocked by drugs that act against dopamine receptors, suggesting that the drug acts on dopamine pathways.

Dopamine Receptor Agonist

Some research suggests dopamine receptor agonist may be effective in treating depression, however studies are few and results are preliminary.

Inositol

Inositol, an alcohol sugar found in fruits, beans grains and nuts may have antidepressant effects in high doses. Inositol may exert its effects by altering intracellular signalling.

Ketamine

Research on the antidepressant effects of ketamine infusions at subanaesthetic doses has consistently shown rapid (4 to 72 hours) responses from single doses, with substantial improvement in mood in the majority of patients and remission in some. However, these effects are often short-lived, and attempts to prolong the antidepressant effect with repeated doses and extended (“maintenance”) treatment have resulted in only modest success.

N-Acetylcysteine

A systematic review and meta-analysis of 5 studies found that N-Acetylcysteine reduces depressive symptoms more than placebo and has good tolerability. N-Acetylecysteine may exert benefits as a precursor to the antioxidant glutathione, thus modulating glutamatergic, neurotropic, and inflammatory pathways.

St John’s Wort

A 2008 Cochrane Collaboration meta-analysis concluded that:

“The available evidence suggests that the hypericum extracts tested in the included trials a) are superior to placebo in patients with major depression; b) are similarly effective as standard antidepressants; c) and have fewer side effects than standard antidepressants. The association of country of origin and precision with effects sizes complicates the interpretation.”

The United States National Centre for Complementary and Integrative Health advice is that “St. John’s wort may help some types of depression, similar to treatment with standard prescription antidepressants, but the evidence is not definitive.” and warns that “Combining St. John’s wort with certain antidepressants can lead to a potentially life-threatening increase of serotonin, a brain chemical targeted by antidepressants. St. John’s wort can also limit the effectiveness of many prescription medicines.”

Rhodiola Rosea

A 2011 review reported Rhodiola rosea “is an adaptogen plant that can be especially helpful in treating asthenic or lethargic depression, and may be combined with conventional antidepressants to alleviate some of their common side effects.” A 6 week double-blind, placebo-controlled, randomised study with 89 patients with mild to moderate depression found that R. rosea statistically significantly reduced depression symptoms, and no side effects were reported.

Saffron

A 2013 meta-analysis found that saffron supplementation significantly reduced depression symptoms compared to placebo, and both saffron supplementation and the antidepressant groups were similarly effective in reducing depression symptoms. A 2015 meta-analysis supported the “efficacy of saffron as compared to placebo in improving the following conditions: depressive symptoms (compared to anti-depressants and placebo), premenstrual symptoms, and sexual dysfunction. In addition, saffron use was also effective in reducing excessive snacking behavior.” The antidepressant effect of saffron stigma extracts may be mediated via its components safranal and crocin: “crocin may act via the uptake inhibition of dopamine and norepinephrine, and safranal via serotonin.” Therapeutic doses of saffron exhibits no significant toxicity in both clinical and experimental investigations.

SAMe

S-Adenosyl methionine (SAMe) is available as a prescription antidepressant in Europe and an over-the-counter dietary supplement in the US. Evidence from 16 clinical trials with a small number of subjects, reviewed in 1994 and 1996 suggested it to be more effective than placebo and as effective as standard antidepressant medication for the treatment of major depression.

Tryptophan and 5-HTP

The amino acid tryptophan is converted into 5-hydroxytryptophan (5-HTP) which is subsequently converted into the neurotransmitter serotonin. Since serotonin deficiency has been recognized as a possible cause of depression, it has been suggested that consumption of tryptophan or 5-HTP may therefore improve depression symptoms by increasing the level of serotonin in the brain. 5-HTP and tryptophan are sold over the counter in North America, but requires a prescription in Europe. The use of 5-HTP instead of tryptophan bypasses the conversion of tryptophan into 5-HTP by the enzyme tryptophan hydroxylase, which is the rate-limiting step in the synthesis of serotonin, and 5-HTP easily crosses the blood–brain barrier unlike tryptophan, which requires a transporter.

Small studies have been performed using 5-HTP and tryptophan as adjunctive therapy in addition to standard treatment for depression. While some studies had positive results, they were criticised for having methodological flaws, and a more recent study did not find sustained benefit from their use. The safety of these medications has not been well studied. Due to the lack of high quality studies, preliminary nature of studies showing effectiveness, the lack of adequate study on their safety, and reports of Eosinophilia-myalgia syndrome from contaminated tryptophan in 1989 and 1990, the use of tryptophan and 5-HTP is not highly recommended or thought to be clinically useful.

Medical Devices

A variety of medical devices are in use or under consideration for treatment of depression including devices that offer electroconvulsive therapy, vagus nerve stimulation, repetitive transcranial magnetic stimulation, and cranial electrotherapy stimulation. The use of such devices in the United States requires approval by the US Food and Drug Administration (FDA) after field trials. In 2010 an FDA advisory panel considered the question of how such field trials should be managed. Factors considered were whether drugs had been effective, how many different drugs had been tried, and what tolerance for suicides should be in field trials.

Electroconvulsive Therapy

Electroconvulsive therapy (ECT) is a standard psychiatric treatment in which seizures are electrically induced in patients to provide relief from psychiatric illnesses. ECT is used with informed consent as a last line of intervention for major depressive disorder. Among the elderly, who often experience depression, the efficacy of ECT is difficult to determine due to the lack of trials comparing ECT to other treatments.

A round of ECT is effective for about 50% of people with treatment-resistant major depressive disorder, whether it is unipolar or bipolar. Follow-up treatment is still poorly studied, but about half of people who respond, relapse with twelve months.

Aside from effects in the brain, the general physical risks of ECT are similar to those of brief general anaesthesia. Immediately following treatment, the most common adverse effects are confusion and memory loss. ECT is considered one of the least harmful treatment options available for severely depressed pregnant women.

A usual course of ECT involves multiple administrations, typically given two or three times per week until the patient is no longer suffering symptoms ECT is administered under anaesthetic with a muscle relaxant. Electroconvulsive therapy can differ in its application in three ways: electrode placement, frequency of treatments, and the electrical waveform of the stimulus. These three forms of application have significant differences in both adverse side effects and symptom remission. After treatment, drug therapy is usually continued, and some patients receive maintenance ECT.

ECT appears to work in the short term via an anticonvulsant effect mostly in the frontal lobes, and longer term via neurotrophic effects primarily in the medial temporal lobe.

Deep Brain Stimulation

The support for the use of deep brain stimulation in treatment-resistant depression comes from a handful of case studies, and this treatment is still in a very early investigational stage. In this technique electrodes are implanted in a specific region of the brain, which is then continuously stimulated. A March 2010 systematic review found that “about half the patients did show dramatic improvement” and that adverse events were “generally trivial” given the younger psychiatric patient population than with movements disorders. Deep brain stimulation is available on an experimental basis only in the United States; no systems are approved by the FDA for this use. It is available in Australia.

Repetitive Transcranial Magnetic Stimulation

Transcranial magnetic stimulation (TMS) or deep transcranial magnetic stimulation is a non-invasive method used to stimulate small regions of the brain. During a TMS procedure, a magnetic field generator, or “coil” is placed near the head of the person receiving the treatment. The coil produces small electric currents in the region of the brain just under the coil via electromagnetic induction. The coil is connected to a pulse generator, or stimulator, that delivers electric current to the coil.

TMS was approved by the FDA for treatment-resistant major depressive disorder in 2008 and as of 2014 clinical evidence supports this use. The American Psychiatric Association, the Canadian Network for Mood and Anxiety Disorders, and the Royal Australia and New Zealand College of Psychiatrists have endorsed rTMS for trMDD.

Vagus Nerve Stimulation

Vagus nerve stimulation (VNS) uses an implanted electrode and generator to deliver electrical pulses to the vagus nerve, one of the primary nerves emanating from the brain. It is an approved therapy for treatment-resistant depression in the EU and US and is sometimes used as an adjunct to existing antidepressant treatment. The support for this method comes mainly from open-label trials, which indicate that several months may be required to see a benefit. The only large double-blind trial conducted lasted only 10 weeks and yielded inconclusive results; VNS failed to show superiority over a sham treatment on the primary efficacy outcome, but the results were more favourable for one of the secondary outcomes. The authors concluded “This study did not yield definitive evidence of short-term efficacy for adjunctive VNS in treatment-resistant depression.”

Cranial Electrotherapy Stimulation

A 2014 Cochrane review found insufficient evidence to determine whether or not Cranial electrotherapy stimulation with alternating current is safe and effective for treating depression.

Transcranial Direct Current Stimulation

A 2016 meta-analysis of transcranial direct current stimulation (tDCS) reported some efficacy of tDCS in the treatment of acute depressive disorder with moderate effect size, and low efficacy in treatment-resistant depression, and that use of 2 mA current strength over 20 minutes per day over a short time span can be considered safe.

Other Treatments

Bright Light Therapy

A meta-analysis of bright light therapy commissioned by the American Psychiatric Association found a significant reduction in depression symptom severity associated with bright light treatment. Benefit was found for both seasonal affective disorder and for non-seasonal depression, with effect sizes similar to those for conventional antidepressants. For non-seasonal depression, adding light therapy to the standard antidepressant treatment was not effective. A meta-analysis of light therapy for non-seasonal depression conducted by Cochrane Collaboration, studied a different set of trials, where light was used mostly in combination with antidepressants or wake therapy. A moderate statistically significant effect of light therapy was found, with response significantly better than control treatment in high-quality studies, in studies that applied morning light treatment, and with patients who respond to total or partial sleep deprivation. Both analyses noted poor quality of most studies and their small size, and urged caution in the interpretation of their results. The short 1-2 weeks duration of most trials makes it unclear whether the effect of light therapy could be sustained in the longer term.

Exercise

The 2013 Cochrane Collaboration review on physical exercise for depression noted that, based upon limited evidence, it is moderately more effective than a control intervention and comparable to psychological or antidepressant drug therapies. Smaller effects were seen in more methodologically rigorous studies. Three subsequent 2014 systematic reviews that included the Cochrane review in their analysis concluded with similar findings: one indicated that physical exercise is effective as an adjunct treatment with antidepressant medication; the other two indicated that physical exercise has marked antidepressant effects and recommended the inclusion of physical activity as an adjunct treatment for mild-moderate depression and mental illness in general. These studies also found smaller effect sizes in more methodologically rigorous studies. All four systematic reviews called for more research in order to determine the efficacy or optimal exercise intensity, duration, and modality. The evidence for brain-derived neurotrophic factor (BDNF) in mediating some of the neurobiological effects of physical exercise was noted in one review which hypothesized that increased BDNF signalling is responsible for the antidepressant effect.

Meditation

Mindfulness meditation programs may help improve symptoms of depression, but they are no better than active treatments such as medication, exercise, and other behavioural therapies.

Music Therapy

A 2009 review found that 3 to 10 sessions of music therapy resulted in a noticeable improvement in depressive symptoms, with still greater improvement after 16 to 51 sessions.

Sleep

Depression is sometimes associated with insomnia – (difficulty in falling asleep, early waking, or waking in the middle of the night). The combination of these two results, depression and insomnia, will only worsen the situation. Hence, good sleep hygiene is important to help break this vicious circle. It would include measures such as regular sleep routines, avoidance of stimulants such as caffeine and management of sleeping disorders such as sleep apnoea.

Smoking Cessation

Quitting smoking cigarettes is associated with reduced depression and anxiety, with the effect “equal or larger than” those of antidepressant treatments.

Total/Partial Sleep Deprivation

Sleep deprivation (skipping a night’s sleep) has been found to improve symptoms of depression in 40-60% of patients. Partial sleep deprivation in the second half of the night may be as effective as an all night sleep deprivation session. Improvement may last for weeks, though the majority (50-80%) relapse after recovery sleep. Shifting or reduction of sleep time, light therapy, antidepressant drugs, and lithium have been found to potentially stabilise sleep deprivation treatment effects.

Shared Care

Shared care, when primary and specialty physicians have joint management of an individual’s health care, has been shown to alleviate depression outcomes.

What are Tricyclic Antidepressants?

Published on by Andrew Marshall83 Comments

Introduction

Tricyclic antidepressants (TCAs) are a class of medications that are used primarily as antidepressants. TCAs were discovered in the early 1950s and were marketed later in the decade. They are named after their chemical structure, which contains three rings of atoms. Tetracyclic antidepressants (TeCAs), which contain four rings of atoms, are a closely related group of antidepressant compounds.

Although TCAs are sometimes prescribed for depressive disorders, they have been largely replaced in clinical use in most parts of the world by newer antidepressants such as

  • Selective serotonin reuptake inhibitors (SSRIs);
  • Serotonin-norepinephrine reuptake inhibitors (SNRIs); and
  • Norepinephrine reuptake inhibitors (NRIs).

Adverse effects have been found to be of a similar level between TCAs and SSRIs.

Brief History

The TCAs were developed amid the “explosive birth” of psychopharmacology in the early 1950s. The story begins with the synthesis of chlorpromazine in December 1950 by Rhône-Poulenc’s chief chemist, Paul Charpentier, from synthetic antihistamines developed by Rhône-Poulenc in the 1940s. Its psychiatric effects were first noticed at a hospital in Paris in 1952. The first widely used psychiatric drug, by 1955 it was already generating significant revenue as an antipsychotic. Research chemists quickly began to explore other derivatives of chlorpromazine.

The first TCA reported for the treatment of depression was imipramine, a dibenzazepine analogue of chlorpromazine code-named G22355. It was not originally targeted for the treatment of depression. The drug’s tendency to induce manic effects was “later described as ‘in some patients, quite disastrous'”. The paradoxical observation of a sedative inducing mania led to testing with depressed patients. The first trial of imipramine took place in 1955 and the first report of antidepressant effects was published by Swiss psychiatrist Roland Kuhn in 1957. Some testing of Geigy’s imipramine, then known as Tofranil, took place at the Münsterlingen Hospital near Konstanz. Geigy later became Ciba-Geigy and eventually Novartis.

Dibenzazepine derivatives are described in US patent 3,074,931 issued 1963-01-22 by assignment to Smith Kline & French Laboratories. The compounds described share a tricyclic backbone different from the backbone of the TCA amitriptyline.

Merck introduced the second member of the TCA family, amitriptyline (Elavil), in 1961. This compound has a different three-ring structure than imipramine.

Medical Uses

The TCAs are used primarily in the clinical treatment of mood disorders such as major depressive disorder (MDD), dysthymia, and treatment-resistant variants. They are also used in the treatment of a number of other medical disorders, including anxiety disorders such as:

Clinical Depression

For many years the TCAs were the first choice for pharmacological treatment of clinical depression. Although they are still considered to be highly effective, they have been increasingly replaced by antidepressants with an improved safety and side effect profile, such as the SSRIs and other newer antidepressants such as the novel reversible MAOI (monoamine oxidase inhibitors) moclobemide. However, tricyclic antidepressants are possibly more effective in treating melancholic depression than other antidepressant drug classes. Newer antidepressants are thought to have fewer and less severe side effects and are also thought to be less likely to result in injury or death if used in a suicide attempt, as the doses required for clinical treatment and potentially lethal overdose are far wider in comparison.

Nonetheless, the TCAs are commonly prescribed for treatment-resistant depression that has failed to respond to therapy with newer antidepressants, they also tend to have fewer emotional blunting and sexual side effects than SSRI antidepressants. They are not considered addictive and are somewhat preferable to the MAOIs. The side effects of the TCAs usually come to prominence before the therapeutic benefits against depression and/or anxiety do, and for this reason, they may potentially be somewhat dangerous, as volition can be increased, possibly giving the patient a greater desire to attempt or commit suicide.

ADHD

The TCAs were used in the past in the clinical treatment of ADHD, though they are not typically used anymore, having been replaced by more effective agents with fewer side effects such as atomoxetine (Strattera, Tomoxetin) and stimulants like methylphenidate (Ritalin, Focalin, Concerta), and amphetamine (Adderall, Attentin, Dexedrine, Vyvanse). ADHD is thought to be caused by an insufficiency of dopamine and norepinephrine activity in the prefrontal cortex of the brain. Most of the TCAs inhibit the reuptake of norepinephrine, though not dopamine, and as a result, they show some efficacy in remedying the disorder. Notably, the TCAs are more effective in treating the behavioural aspects of ADHD than the cognitive deficits, as they help limit hyperactivity and impulsivity, but have little to no benefits on attention.

Chronic Pain

The TCAs show efficacy in the clinical treatment of a number of different types of chronic pain, notably neuralgia or neuropathic pain and fibromyalgia. The precise mechanism of action in explanation of their analgesic efficacy is unclear, but it is thought that they indirectly modulate the opioid system in the brain downstream via serotonergic and noradrenergic neuromodulation, among other properties. They are also effective in migraine prophylaxis, though not in the instant relief of an acute migraine attack. They may also be effective to prevent chronic tension headaches.

Side Effects

Many side effects may be related to the antimuscarinic properties of the TCAs. Such side effects are relatively common and may include dry mouth, dry nose, blurry vision, lowered gastrointestinal motility or constipation, urinary retention, cognitive and/or memory impairment, and increased body temperature.

Other side effects may include drowsiness, anxiety, emotional blunting (apathy/anhedonia), confusion, restlessness, dizziness, akathisia, hypersensitivity, changes in appetite and weight, sweating, muscle twitches, weakness, nausea and vomiting, hypotension, tachycardia, and rarely, irregular heart rhythms. Twitching, hallucinations, delirium and coma are also some of the toxic effects caused by overdose. Rhabdomyolysis or muscle breakdown has been rarely reported with this class of drugs as well.

Tolerance to these adverse effects of these drugs often develops if treatment is continued. Side effects may also be less troublesome if treatment is initiated with low doses and then gradually increased, although this may also delay the beneficial effects.

TCAs can behave like class 1A antiarrhythmics, as such, they can theoretically terminate ventricular fibrillation, decrease cardiac contractility and increase collateral blood circulation to ischemic heart muscle. Naturally, in overdose, they can be cardiotoxic, prolonging heart rhythms and increasing myocardial irritability.

New research has also revealed compelling evidence of a link between long-term use of anticholinergic medications like TCAs and dementia. Although many studies have investigated this link, this was the first study to use a long-term approach (over seven years) to find that dementias associated with anticholinergics may not be reversible even years after drug use stops. Anticholinergic drugs block the action of acetylcholine, which transmits messages in the nervous system. In the brain, acetylcholine is involved in learning and memory.

Discontinuation

Antidepressants in general may produce withdrawal. However, since the term “withdrawal” has been linked to addiction to recreational drugs like opioids, the medical profession and pharmaceutical public relations prefer that a different term be used, hence “discontinuation syndrome.” Discontinuation symptoms can be managed by a gradual reduction in dosage over a period of weeks or months to minimise symptoms. In tricyclics, discontinuation syndrome symptoms include anxiety, insomnia, headache, nausea, malaise, or motor disturbance.

Overdose

Refer to Tricyclic Antidepressant Overdose.

TCA overdose is a significant cause of fatal drug poisoning. The severe morbidity and mortality associated with these drugs is well documented due to their cardiovascular and neurological toxicity. Additionally, it is a serious problem in the paediatric population due to their inherent toxicity and the availability of these in the home when prescribed for bed-wetting and depression. In the event of a known or suspected overdose, medical assistance should be sought immediately.

A number of treatments are effective in a TCA overdose.

An overdose on TCA is especially fatal as it is rapidly absorbed from the GI tract in the alkaline conditions of the small intestines. As a result, toxicity often becomes apparent in the first hour after an overdose. However, symptoms may take several hours to appear if a mixed overdose has caused delayed gastric emptying.

Many of the initial signs are those associated to the anticholinergic effects of TCAs such as dry mouth, blurred vision, urinary retention, constipation, dizziness, and emesis (or vomiting). Due to the location of norepinephrine receptors all over the body, many physical signs are also associated with a TCA overdose:

  • Anticholinergic effects: Altered mental status (e.g., agitation, confusion, lethargy, etc.), resting sinus tachycardia, dry mouth, mydriasis (pupil dilation), and fever.
  • Cardiac effects: Hypertension (early and transient, should not be treated), tachycardia, orthostasis and hypotension, arrhythmias (including ventricular tachycardia and ventricular fibrillation, most serious consequence) / ECG changes (prolonged QRS, QT, and PR intervals).
  • CNS effects: Syncope, seizure, coma, myoclonus, hyperreflexia.
  • Pulmonary effects: Hypoventilation resulting from CNS depression.
  • Gastrointestinal effects: Decreased or absent bowel sounds.

Treatment of TCA overdose depends on severity of symptoms:

Initially, gastric decontamination of the patient is achieved by administering, either orally or via a nasogastric tube, activated charcoal pre-mixed with water, which adsorbs the drug in the gastrointestinal tract (most useful if given within 2 hours of drug ingestion). Other decontamination methods such as stomach pumps, gastric lavage, whole bowel irrigation, or (ipecac induced) emesis, are not recommended in TCA poisoning.

If there is metabolic acidosis, intravenous infusion of sodium bicarbonate is recommended by Toxbase.org, the UK and Ireland poisons advice database (TCAs are protein bound and become less bound in more acidic conditions, so by reversing the acidosis, protein binding increases and bioavailability thus decreases – the sodium load may also help to reverse the Na+ channel blocking effects of the TCA).

Interactions

The TCAs are highly metabolised by the cytochrome P450 (CYP) hepatic enzymes. Drugs that inhibit cytochrome P450 (for example cimetidine, methylphenidate, fluoxetine, antipsychotics, and calcium channel blockers) may produce decreases in the TCAs’ metabolism, leading to increases in their blood concentrations and accompanying toxicity. The major factor that distinguishes SSRI’s amongst one another is the inhibition of select CYP enzymes. Drugs that prolong the QT interval including antiarrhythmics such as quinidine, the antihistamines astemizole and terfenadine, and some antipsychotics may increase the chance of ventricular dysrhythmias. TCAs may enhance the response to alcohol and the effects of barbiturates and other CNS depressants. Side effects may also be enhanced by other drugs that have antimuscarinic properties.

Pharmacology

The majority of the TCAs act primarily as SNRIs by blocking the serotonin transporter (SERT) and the norepinephrine transporter (NET), which results in an elevation of the synaptic concentrations of these neurotransmitters, and therefore an enhancement of neurotransmission. Notably, with the sole exception of amineptine, the TCAs have negligible affinity for the dopamine transporter (DAT), and therefore have no efficacy as dopamine reuptake inhibitors (DRIs). Both serotonin and norepinephrine have been highly implicated in depression and anxiety, and it has been shown that facilitation of their activity has beneficial effects on these mental disorders.

In addition to their reuptake inhibition, many TCAs also have high affinity as antagonists at the 5-HT2 (5-HT2A and 5-HT2C), 5-HT6, 5-HT7, α1-adrenergic, and NMDA receptors, and as agonists at the sigma receptors (σ1 and σ2), some of which may contribute to their therapeutic efficacy, as well as their side effects. The TCAs also have varying but typically high affinity for antagonising the H1 and H2 histamine receptors, as well as the muscarinic acetylcholine receptors. As a result, they also act as potent antihistamines and anticholinergics. These properties are often beneficial in antidepressants, especially with comorbid anxiety, as it provides a sedative effect.

Most, if not all, of the TCAs also potently inhibit sodium channels and L-type calcium channels, and therefore act as sodium channel blockers and calcium channel blockers, respectively. The former property is responsible for the high mortality rate upon overdose seen with the TCAs via cardiotoxicity. It may also be involved in their efficacy as analgesics, however.

In summary, tricyclic antidepressants can act through NMDA antagonism, opioidergic effects, sodium, potassium and calcium channel blocking, through interfering with the reuptake of serotonin and acting as antagonists to SHAM (serotonin, histamine, alpha, muscarinic) receptors. Thus their dangerous side effect profile limits their use in daily practice.

Chemistry

There are two major groups of TCAs in terms of chemical structure, which most, but not all, TCAs fall into. The groupings are based on the tricyclic ring system. They are the dibenzazepines (imipramine, desipramine, clomipramine, trimipramine, lofepramine) and the dibenzocycloheptadienes (amitriptyline, nortriptyline, protriptyline, butriptyline). Minor TCA groups based on ring system include the dibenzoxepins (doxepin), the dibenzothiepines (dosulepin), and the dibenzoxazepines (amoxapine). In addition to classification based on the ring system, TCAs can also be usefully grouped based on the number of substitutions of the side chain amine. These groups include the tertiary amines (imipramine, clomipramine, trimipramine, amitriptyline, butriptyline, doxepin, dosulepin) and the secondary amines (desipramine, nortriptyline, protriptyline). Lofepramine is technically a tertiary amine, but acts largely as a prodrug of desipramine, a secondary amine, and hence is more similar in profile to the secondary amines than to the tertiary amines. Amoxapine does not have the TCA side chain and hence is neither a tertiary nor secondary amine, although it is often grouped with the secondary amines due to sharing more in common with them.

Society and Culture

Recreational Use

A very small number of cases involving non-medical use of antidepressants have been reported over the past 30 years. According to the US government classification of psychiatric medications, TCAs are “non-abusable” and generally have low abuse potential. Nonetheless due to their atypical MOA, amineptine and tianeptine (dopamine reuptake inhibition and μ-opioid receptor agonism, respectively) are the two TCAs with the highest addiction and abuse potential. Despite tianeptine’s recreational value, many people use it as a nootropic and follow other countries’ usage guidelines, such as France, as a way to treat their depression if other antidepressants do not work. Their prescription guidelines are 12.5 mg three times a day, and not to exceed 50 mg in one day. Tianeptine has no recreational value when taken at that dosage and kept under 50 mg a day. Many people report that tianeptine has treated their depression when SSRI’s or SNRI’s have not. Several cases of the misuse of amitriptyline alone or together with methadone or in other drug dependent patients and of dosulepin with alcohol or in methadone patients have been reported.

List of TCAs

Those that preferentially inhibit the reuptake of serotonin (by at least 10-fold over norepinephrine) include:

  • Butriptyline† (Evadyne) (relatively weak serotonin reuptake inhibitor).
  • Clomipramine (Anafranil).
  • Imipramine (Tofranil, Janimine, Praminil).
  • Trimipramine (Surmontil) (relatively weak serotonin reuptake inhibitor).

Those that preferentially inhibit the reuptake of norepinephrine (by at least 10-fold over serotonin) include:

  • Desipramine (Norpramin, Pertofrane).
  • Dibenzepin‡ (Noveril, Victoril).
  • Lofepramine§ (Lomont, Gamanil).
  • Maprotiline (Ludiomil) – can be classed with the TCAs though more frequently classed with the TeCAs.
  • Nortriptyline (Pamelor, Aventyl, Norpress).
  • Protriptyline (Vivactil).

Whereas either fairly balanced reuptake inhibitors of serotonin and norepinephrine or unspecified inhibitors include:

  • Amitriptyline (Elavil, Endep).
  • Amitriptylinoxide (Amioxid, Ambivalon, Equilibrin).
  • Amoxapine (Asendin) – can be classed with the TeCAs but more frequently classed with the TCAs.
  • Demexiptiline† (Deparon, Tinoran).
  • Dimetacrine† (Istonil, Istonyl, Miroistonil).
  • Dosulepin§ (Prothiaden).
  • Doxepin (Adapin, Sinequan).
  • Fluacizine† (Phtorazisin).
  • Imipraminoxide† (Imiprex, Elepsin).
  • Melitracen§ (Deanxit, Dixeran, Melixeran, Trausabun).
  • Metapramine† (Timaxel).
  • Nitroxazepine‡ (Sintamil).
  • Noxiptiline‡ (Agedal, Elronon, Nogedal).
  • Pipofezine‡ (Azafen/Azaphen).
  • Propizepine† (Depressin, Vagran).
  • Quinupramine† (Kevopril, Kinupril, Adeprim, Quinuprine).

And the following are TCAs that act via main mechanisms other than serotonin or norepinephrine reuptake inhibition:

  • Amineptine‡ (Survector, Maneon, Directim) – norepinephrine–dopamine reuptake inhibitor.
  • Iprindole† (Prondol, Galatur, Tetran) – 5-HT2 receptor antagonist.
  • Opipramol‡ (Insidon, Pramolan, Ensidon, Oprimol) – σ receptor agonist.
  • Tianeptine § (Stablon, Coaxil, Tatinol) – atypical μ-opioid receptor agonist.

Legend:

  • † indicates products which have been withdrawn from the market worldwide.
  • ‡ indicates products which are not available in any country in which English is an official language.
  • § indicates products which are not available in the United States, but are available in other English-speaking countries such as Australia, Canada, United Kingdom, etc.
  • Bolded names indicates products which are available in at least three countries in which English is an official language.

What are Tetracyclic Antidepressants?

Published on by Andrew Marshall15 Comments

Introduction

Tetracyclic antidepressants (TeCAs) are a class of antidepressants that were first introduced in the 1970s.

They are named after their tetracyclic chemical structure, containing four rings of atoms, and are closely related to the tricyclic antidepressants (TCAs), which contain three rings of atoms.

List of TeCAs

Marketed

  • Maprotiline (Ludiomil): can also be classified as a TCA and grouped with the secondary amines
  • Mianserin (Tolvon).
  • Mirtazapine (Remeron).
  • Setiptiline (Tecipul).
  • Drugs that contain four rings not all fused together but are sometimes still classified as TeCAs include:
    • Amoxapine (Asendin):– often classified as a TCA and grouped with the secondary amines.
  • Miscellaneous:
    • Benzoctamine (Tacitin): a tetracyclic compound and is closely related to maprotiline, with the two compounds differing only in the length of their side chain, but benzoctamine is not used as an antidepressant and is instead used as an anxiolytic.
    • Loxapine (Adasuve, Loxitane): a typical antipsychotic that produces amoxapine as a major metabolite and is said to have antidepressant effects, but it is not usually regarded as a TeCA.
  • Drugs that contain four rings not all fused together but could still be classified as tetracyclic include:
    • Mazindol (Mazanor, Sanorex): a monoamine reuptake inhibitor used as an appetite suppressant and with potential antidepressant effects, but not classified as a TeCA.

Never Marketed

  • Aptazapine (CGS-7525A): a close analogue of mirtazapine.
  • Esmirtazapine (ORG-50,081): the (S)-(+) enantiomer of mirtazapine.
  • Oxaprotiline (C 49-802 BDA): a close analogue of maprotiline.
  • Drugs that contain four rings not all fused together but could still be classified as tetracyclic include:
    • Ciclazindol (WY-23,409): a close analogue of mazindol.

Pharmacology

TeCAs have diverse pharmacology and differ from TCAs in a number of ways. With the exception of amoxapine, TeCAs do not inhibit the reuptake of serotonin. However, aside from mirtazapine, they do inhibit the reuptake of norepinephrine. TeCAs block the serotonin 5-HT2 receptors similarly to TCAs. Besides mirtazapine, they also block the α1-adrenergic receptor. Conversely, whereas TCAs have relatively low affinity for the α2-adrenergic receptor, mianserin and mirtazapine potently antagonise this receptor, and this action is thought to be involved in their antidepressant effects. TeCAs block the histamine H1 receptor similarly to the TCAs, but tend to be even stronger antihistamines than TCAs. On the other hand, in contrast to almost all TCAs, TeCAs have only low affinity for the muscarinic acetylcholine receptors, and for this reason, are associated with few or no anticholinergic side effects. Mianserin and mirtazapine are far less toxic than TCAs in overdose.

Binding Profiles

The binding profiles of various TeCAs in terms of their affinities (Ki, nM) for various receptors and transporters are as follows:

CompoundSERTNETDAT5-HT1A5-HT2A5-HT2B5-HT2C5-HT35-HT65-HT7α1α2D2H1H2mACh
Amoxapine58164,310ND0.5ND2.0ND6.0-5041502,6003.6-1607.9-25ND1,000
Maprotiline5,80011-121,000ND51ND122NDND50909,400350-6650.79-2.0776570
Mianserin4,000719,400400-2,6001.6-201.6-550.63-6.55.8-30055-8148-56343.8-73≥2,100.30-1.7437820
Mirtazapine>10,000≥4,600>10,000≥3,3306.3-692008.9-397.9ND265316-1,81518-88>5,4540.14-1.6>10,000670
Setiptiline>10,000220>10,000NDNDNDNDNDNDNDND24NDNDNDND

Notes:

  • Values are Ki (nM).
    • The smaller the value, the more strongly the drug binds to the site.
    • For assay species and references, see the individual drug articles.
    • Most but not all values are for human proteins.
  • The TeCAs act as antagonists or inverse agonists of the receptors and as inhibitors of the transporters.