Tag: Atypical Antidepressant

What is Butriptyline?

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Introduction

Butriptyline, sold under the brand name Evadyne among others, is a tricyclic antidepressant (TCA) that has been used in the United Kingdom and several other European countries for the treatment of depression but appears to no longer be marketed. Along with trimipramine, iprindole, and amoxapine, it has been described as an “atypical” or “second-generation” TCA due to its relatively late introduction and atypical pharmacology. It was very little-used compared to other TCAs, with the number of prescriptions dispensed only in the thousands.

Brief History

Butriptyline was developed by Wyeth, an American pharmaceutical company, and introduced in the United Kingdom in either 1974 or 1975.

Medical Uses

Butriptyline was used in the treatment of depression. It was usually used at dosages of 150-300 mg/day.

Side Effects

Butriptyline is closely related to amitriptyline, and produces similar effects as other TCAs, but its side effects like sedation are said to be reduced in severity and it has a lower risk of interactions with other medications.

Butriptyline has potent antihistamine effects, resulting in sedation and somnolence. It also has potent anticholinergic effects, resulting in side effects like dry mouth, constipation, urinary retention, blurred vision, and cognitive/memory impairment. The drug has relatively weak effects as an alpha-1 blocker and has no effects as a norepinephrine reuptake inhibitor, so is associated with little to no antiadrenergic and adrenergic side effects.

Overdose

Refer to Tricyclic Antidepressant Overdose.

Pharmacology

Pharmacodynamics

In vitro, butriptyline is a strong antihistamine and anticholinergic, moderate 5-HT2 and α1-adrenergic receptor antagonist, and very weak or negligible monoamine reuptake inhibitor. These actions appear to confer a profile similar to that of iprindole and trimipramine with serotonin-blocking effects as the apparent predominant mediator of mood-lifting efficacy.

However, in small clinical trials, using similar doses, butriptyline was found to be similarly effective to amitriptyline and imipramine as an antidepressant, despite the fact that both of these TCAs are far stronger as both 5-HT2 antagonists and serotonin–norepinephrine reuptake inhibitors. As a result, it may be that butriptyline has a different mechanism of action, or perhaps functions as a prodrug in the body to a metabolite with different pharmacodynamics.

Pharmacokinetics

Therapeutic concentrations of butriptyline are in the range of 60-280 ng/mL (204-954 nmol/L). Its plasma protein binding is greater than 90%.

Chemistry

Butriptyline is a tricyclic compound, specifically a dibenzocycloheptadiene, and possesses three rings fused together with a side chain attached in its chemical structure. Other dibenzocycloheptadiene TCAs include amitriptyline, nortriptyline, and protriptyline. Butriptyline is an analogue of amitriptyline with an isobutyl side chain instead of a propylidene side chain. It is a tertiary amine TCA, with its side chain-demethylated metabolite norbutriptyline being a secondary amine. Other tertiary amine TCAs include amitriptyline, imipramine, clomipramine, dosulepin (dothiepin), doxepin, and trimipramine. The chemical name of butriptyline is 3-(10,11-dihydro-5H-dibenzo[a,d]cycloheptene-5-yl)-N,N,2-trimethylpropan-1-amine and its free base form has a chemical formula of C21H27N with a molecular weight of 293.446 g/mol. The drug has been used commercially both as the free base and as the hydrochloride salt. The CAS Registry Number of the free base is 15686-37-0 and of the hydrochloride is 5585-73-9.

Society and Culture

Generic Names

Butriptyline is the English and French generic name of the drug and its International Non-Propriety Name (INN), British Approved Name (BAN), and Denomination Commune Francaise (DCF), while butriptyline hydrochloride is its BANM and (United States Adopted Name (USAN). Its generic name in Latin is butriptylinum, in German is butriptylin, and in Spanish is butriptylina.

Brand Names

Butriptyline has been marketed under the brand names Evadene, Evadyne, Evasidol, and Centrolese.

Availability

Butriptyline has been marketed in Europe, including in the United Kingdom, Belgium, Luxembourg, Austria, and Italy.

This page is based on the copyrighted Wikipedia article < https://en.wikipedia.org/wiki/Butriptyline >; 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 Amineptine?

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Introduction

Amineptine, formerly sold under the brand name Survector among others, is an atypical antidepressant of the tricyclic antidepressant (TCA) family.

It acts as a selective and mixed dopamine reuptake inhibitor and releasing agent, and to a lesser extent as a norepinephrine reuptake inhibitor.

Amineptine was developed by the French Society of Medical research in the 1960s. Introduced in France in 1978 by the pharmaceutical company Servier, amineptine soon gained a reputation for abuse due to its short-lived, but pleasant, stimulant effect experienced by some patients.

After its release into the European market, cases of hepatotoxicity emerged, some serious. This, along with the potential for abuse, led to the suspension of the French marketing authorization for Survector in 1999.

Amineptine was never approved by the US Food and Drug Administration (FDA) for marketing in the US, meaning that it is not legal to market or sell amineptine for any medical uses in the US.

Medical Uses

Amineptine was approved in France for severe clinical depression of endogenous origin in 1978.

Contraindications

  • Chorea
  • Hypersensitivity: Known hypersensitivity to amineptine, in particular antecedents of hepatitis after dosage of the product.
  • MAO inhibitors.

Precautions for Use

Warnings and precautions before taking amineptine:

  • Breast feeding.
  • Children less than 15-year of age.
  • General anaesthesia: Discontinue the drug 24 to 48 hours before anaesthesia.
  • Official sports/Olympic Games: Prohibited substance.
  • Pregnancy (first trimester).

Effects on the Foetus

  • Lacking information in humans.
  • Non-teratogenic in rodents.

Side Effects

Dermatological

Severe acne due to amineptine was first reported in 1988 by various authors – Grupper, Thioly-Bensoussan, Vexiau, Fiet, Puissant, Gourmel, Teillac, Levigne, to name a few – simultaneously in the same issue of Annales de dermatologie et de vénéréologie and in the 12 March 1988 issue of The Lancet. A year later, Dr Martin-Ortega and colleagues in Barcelona, Spain reported a case of “acneiform eruption” in a 54-year-old woman whose intake of amineptine was described as “excessive.” One year after that, Vexiau and colleagues reported six women, one of whom never admitted to using amineptine, getting severe acne concentrated in the face, back and thorax, the severity of which varied with the dosage. Most of them were treated unsuccessfully with isotretinoin (Accutane) for about 18 months; two of the three that discontinued amineptine experienced a reduction in cutaneous symptoms, with the least affected patient going into remission.

Psychiatric

Psychomotor excitation can very rarely occur with this drug.

  • Insomnia.
  • Irritability.
  • Nervousness.
  • Suicidal ideation. Seen early in the treatment, by lifting of psychomotor inhibition.

Abuse and Dependence

The risk of addiction is low, but exists nonetheless. Between 1978 and 1988, there were 186 cases of amineptine addiction reported to the French Regional Centres of Pharmacovigilance; an analysis of 155 of those cases found that they were predominantly female, and that two-thirds of cases had known risk factors for addiction. However, a 1981 study of known opiate addicts and schizophrenia patients found no drug addiction in any of the subjects. In a 1990 study of eight amineptine dependence cases, the gradual withdrawal of amineptine could be achieved without problems in six people; in two others, anxiety, psychomotor agitation, and/or bulimia appeared.

Withdrawal

Pharmacodependence is very common with amineptine compared to other antidepressants. A variety of psychological symptoms can occur during withdrawal from amineptine, such as anxiety and agitation.

Cardiovascular

Very rarely:

  • Arterial hypotension.
  • Palpitations.
  • Vasomotor episode.

Hepatic

Amineptine can rarely cause hepatitis, of the cytolytic, cholestatic varieties. Amineptine-induced hepatitis, which is sometimes preceded by a rash, is believed to be due to an immunoallergic reaction. It resolves upon discontinuation of the offending drug. The risk of getting this may or may not be genetically determined.

Additionally, amineptine is known to rarely elevate transaminases, alkaline phosphatase, and bilirubin.

Mixed hepatitis, which is very rare, generally occurs between the 15th and 30th day of treatment. Often preceded by sometimes intense abdominal pains, nausea, vomiting or a rash, the jaundice is variable. Hepatitis is either of mixed type or with cholestatic prevalence. The evolution was, in all the cases, favourable to the discontinuation of the drug. The mechanism is discussed (immunoallergic and/or toxic).

In circa 1994 Spain, there was a case associating acute pancreatitis and mixed hepatitis, after three weeks of treatment.

Lazaros and colleagues at the Western Attica General Hospital in Athens, Greece reported two cases of drug induced hepatitis 18 and 15 days of treatment.

One case of cytolytic hepatitis occurred after ingestion of only one tablet.

Gastrointestinal

Acute pancreatitis (very rare) A case associating acute pancreatitis and mixed hepatitis after three weeks of treatment.

Immunological

In 1989, Sgro and colleagues at the Centre de Pharmacovigilance in Dijon reported a case of anaphylactic shock in a woman who had been taking amineptine.

Pharmacology

Pharmacodynamics

Amineptine inhibits the reuptake of dopamine and, to a much lesser extent, of norepinephrine. In addition, it has been found to induce the release of dopamine. However, amineptine is much less efficacious as a dopamine releasing agent relative to D-amphetamine, and the drug appears to act predominantly as a dopamine reuptake inhibitor. In contrast to the case for dopamine, amineptine does not induce the release of norepinephrine, and hence acts purely as a norepinephrine reuptake inhibitor. Unlike other TCAs, amineptine interacts very weakly or not at all with the serotonin, adrenergic, dopamine, histamine, and muscarinic acetylcholine receptors. The major metabolites of amineptine have similar activity to that of the parent compound, albeit with lower potency.

No human data appear to be available for binding or inhibition of the monoamine transporters by amineptine.

Pharmacokinetics

Peak plasma levels of amineptine following a single 100 mg oral dose have been found to range between 277 and 2,215 ng/mL (818-6,544 nM), with a mean of 772 ng/mL (2,281 nM), whereas maximal plasma concentrations of its major metabolite ranged between 144 and 1,068 ng/mL (465–3,452 nM), with a mean of 471 ng/mL (1,522 nM). After a single 200 mg oral dose of amineptine, mean peak plasma levels of amineptine were around 750 to 940 ng/mL (2,216-2,777 nM), while those of its major metabolite were about 750 to 970 ng/mL (2,216-3,135 nM). The time to peak concentrations is about 1 hour for amineptine and 1.5 hours for its major metabolite. The elimination half-life of amineptine is about 0.80 to 1.0 hours and that of its major metabolite is about 1.5 to 2.5 hours. Due to their very short elimination half-lives, amineptine and its major metabolite do not accumulate significantly with repeated administration.

Society and Culture

Brand Names

Amineptine has been sold under a variety of brand names including Survector, Maneon, Directim, Neolior, Provector, and Viaspera.

Legal Status

It had been proposed that Amineptine become a Schedule I controlled substance in the United States in July 2021.

This page is based on the copyrighted Wikipedia article <https://en.wikipedia.org/wiki/Amineptine&gt;; 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 a Second-Generation Antidepressant?

Published on by Andrew Marshall1 Comment

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 Nefazodone?

Published on by Andrew Marshall4 Comments

Introduction

Nefazodone, sold formerly under the brand names Serzone, Dutonin, and Nefadar among others, is an atypical antidepressant which was first marketed by Bristol-Myers Squibb (BMS) in 1994 but has since largely been discontinued.

BMS withdrew it from the market by 2004 due to decreasing sales due to the rare incidence of severe liver damage and the onset of generic competition. The incidence of severe liver damage is approximately 1 in every 250,000 to 300,000 patient-years. Generic versions were introduced in 2003.

Nefazodone is a phenylpiperazine compound and is related to trazodone. It has been described as a serotonin antagonist and reuptake inhibitor (SARI) due to its combined actions as a potent serotonin 5-HT2A receptor and 5-HT2C receptor antagonist and weak serotonin-norepinephrine-dopamine reuptake inhibitor (SNDRI).

Brief History

Nefazodone was discovered by scientists at Bristol-Myers Squibb (BMS) who were seeking to improve on trazodone by reducing its sedating qualities.

BMS obtained marketing approvals worldwide for nefazodone in 1994. It was marketed in the US under the brand name Serzone and in Europe under the brand name Dutonin.

In 2002, the US Food and Drug Administration (FDA) obligated BMS to add a black box warning about potential fatal liver toxicity to the drug label. Worldwide sales in 2002 were $409 million.

In 2003 Public Citizen filed a citizen petition asking the FDA to withdraw the marketing authorisation in the US, and in early 2004 the organisation sued the FDA to attempt to force withdrawal of the drug. The FDA issued a response to the petition in June 2004 and filed a motion to dismiss, and Public Citizen withdrew the suit.

Generic versions were introduced in the US in 2003 and Health Canada withdrew the marketing authorization that year.

Sales of nefazodone were about $100 million in 2003. By that time it was also being marketed under the additional brand names Serzonil, Nefadar, and Rulivan.

In April 2004, BMS announced that it was going discontinue the sale of Serzone in the US in June 2004 and said that this was due to declining sales. By that time BMS had already withdrawn the drug from the market in Europe, Australia, New Zealand and Canada.

As of 2012 generic nefazodone was available in the US.

Medical Uses

Nefazodone is used to treat major depressive disorder, aggressive behaviour, and panic disorder.

Available Forms

Nefazodone is available as 50 mg, 100 mg, 150 mg, 200 mg, and 250 mg tablets for oral ingestion.

Side Effects

Nefazodone can cause severe liver damage, leading to a need for liver transplant, and death. The incidence of severe liver damage is approximately 1 in every 250,000 to 300,000 patient-years. By the time that it started to be withdrawn in 2003, nefazodone had been associated with at least 53 cases of liver injury, with 11 deaths, in the United States, and 51 cases of liver toxicity, with 2 cases of liver transplantation, in Canada. In a Canadian study which found 32 cases in 2002, it was noted that databases like that used in the study tended to include only a small proportion of suspected drug reactions.

Common and mild side effects of nefazodone reported in clinical trials more often than placebo include dry mouth (25%), sleepiness (25%), nausea (22%), dizziness (17%), blurred vision (16%), weakness (11%), lightheadedness (10%), confusion (7%), and orthostatic hypotension (5%). Rare and serious adverse reactions may include allergic reactions, fainting, painful/prolonged erection, and jaundice.

Nefazodone is not especially associated with increased appetite and weight gain.

Interactions

Nefazodone is a potent inhibitor of CYP3A4, and may interact adversely with many commonly used medications that are metabolized by CYP3A4.

Pharmacology

Pharmacodynamics

Nefazodone acts primarily as a potent antagonist of the serotonin 5-HT2A receptor and to a lesser extent of the serotonin 5-HT2C receptor. It also has high affinity for the α1-adrenergic receptor and serotonin 5-HT1A receptor, and relatively lower affinity for the α2-adrenergic receptor and dopamine D2 receptor. Nefazodone has low but significant affinity for the serotonin, norepinephrine, and dopamine transporters as well, and therefore acts as a weak serotonin-norepinephrine-dopamine reuptake inhibitor (SNDRI). It has low but potentially significant affinity for the histamine H1 receptor, where it is an antagonist, and hence may have some antihistamine activity. Nefazodone has negligible activity at muscarinic acetylcholine receptors, and accordingly, has no anticholinergic effects.

Pharmacokinetics

The bioavailability of nefazodone is low and variable, about 20%. Its plasma protein binding is approximately 99%, but it is bound loosely.

Nefazodone is metabolized in the liver, with the main enzyme involved thought to be CYP3A4. The drug has at least four active metabolites, which include hydroxynefazodone, para-hydroxynefazodone, triazoledione, and meta-chlorophenylpiperazine. Nefazodone has a short elimination half-life of about 2 to 4 hours. Its metabolite hydroxynefazodone similarly has an elimination half-life of about 1.5 to 4 hours, whereas the elimination half-lives of triazoledione and mCPP are longer at around 18 hours and 4 to 8 hours, respectively. Due to its long elimination half-life, triazole is the major metabolite and predominates in the circulation during nefazodone treatment, with plasma levels that are 4 to 10 times higher than those of nefazodone itself. Conversely, hydroxynefazodone levels are about 40% of those of nefazodone at steady state. Plasma levels of mCPP are very low at about 7% of those of nefazodone; hence, mCPP is only a minor metabolite. mCPP is thought to be formed from nefazodone specifically by CYP2D6.

The ratios of brain-to-plasma concentrations of mCPP to nefazodone are 47:1 in mice and 10:1 in rats, suggesting that brain exposure to mCPP may be much higher than plasma exposure. Conversely, hydroxynefazodone levels in the brain are 10% of those in plasma in rats. As such, in spite of its relatively low plasma concentrations, brain exposure to mCPP may be substantial, whereas that of hydroxynefazodone may be minimal.

Chemistry

Nefazodone is a phenylpiperazine; it is an alpha-phenoxyl derivative of etoperidone which in turn was a derivative of trazodone.

Society and Culture

Generic Names

Nefazodone is the generic name of the drug and its INN and BAN, while néfazodone is its DCF and nefazodone hydrochloride is its USAN and USP.

Brand Names

Nefazodone has been marketed under a number of brand names including Dutonin (AT, ES, IE, UK), Menfazona (ES), Nefadar (CH, DE, NO, SE), Nefazodone BMS (AT), Nefazodone Hydrochloride Teva (US), Reseril (IT), Rulivan (ES), and Serzone (AU, CA, US). As of 2017, it remains available only on a limited basis as Nefazodone Hydrochloride Teva in the United States.

Research

The use of nefazodone to prevent migraine has been studied, due to its antagonistic effects on the 5-HT2A and 5-HT2C receptors.

What is Agomelatine?

Published on by Andrew Marshall1 Comment

Introduction

Agomelatine is an atypical antidepressant used to treat major depressive disorder.

One review found that it is as effective as other antidepressants with similar discontinuation rates overall but less discontinuations due to side effects. Another review also found it was similarly effective to many other antidepressants.

Common side effects include weight gain, fatigue, liver problems, nausea, headaches, and anxiety. Due to potential liver problems ongoing blood tests are recommended. Its use is not recommended in people with dementia or over the age of 75. There is tentative evidence that it may have fewer side effects than some other antidepressants. It works by stimulating melatonin receptors and blocking serotonin receptors.

Agomelatine was approved for medical use in Europe in 2009 and Australia in 2010. Its use is not approved in the United States and efforts to get approval were ended in 2011. It was developed by the pharmaceutical company Servier.

Brief History

Agomelatine was discovered and developed by the European pharmaceutical company Servier Laboratories Ltd. Servier continued to develop the drug and conduct phase III trials in the European Union.

In March 2005, Servier submitted agomelatine to the European Medicines Agency (EMA) under the trade names Valdoxan and Thymanax. On 27 July 2006, the Committee for Medical Products for Human Use (CHMP) of the EMA recommended a refusal of the marketing authorisation. The major concern was that efficacy had not been sufficiently shown, while there were no special concerns about side effects. In September 2007, Servier submitted a new marketing application to the EMA.

In March 2006, Servier announced it had sold the rights to market agomelatine in the United States to Novartis. It was undergoing several phase III clinical trials in the US, and until October 2011 Novartis listed the drug as scheduled for submission to the FDA no earlier than 2012. However, the development for the US market was discontinued in October 2011, when the results from the last of those trials became available.

It received approval from the European Medicines Agency (EMA) for marketing in the European Union in February 2009 and approval from the Therapeutic Goods Administration (TGA) for marketing in Australia in August 2010.

Medical Uses

Major Depressive Disorder

Agomelatine is used for the treatment of major depressive episodes in adults in Europe. Ten placebo controlled trials have been performed to investigate the short term efficacy of agomelatine in major depressive disorder. At the end of treatment, significant efficacy was demonstrated in six of the ten short-term double-blind placebo-controlled studies. Two were considered “failed” trials, as comparators of established efficacy failed to differentiate from placebo. Efficacy was also observed in more severely depressed patients in all positive placebo-controlled studies. The maintenance of antidepressant efficacy was demonstrated in a relapse prevention study. One meta-analysis found agomelatine to be as effective as standard antidepressants.

A meta-analysis found that agomelatine is effective in treating severe depression. Its antidepressant effect is greater for more severe depression. In people with a greater baseline score (>30 on HAMD17 scale), the agomelatine-placebo difference was of 4.53 points. Controlled studies in humans have shown that agomelatine is at least as effective as the SSRI antidepressants paroxetine, sertraline, escitalopram, and fluoxetine in the treatment of major depression. A 2018 meta-study comparing 21 antidepressants found agomelatine was one of the more tolerable, yet effective antidepressants.

However, the body of research on agomelatine has been substantially affected by publication bias, prompting analyses which take into account both published and unpublished studies. These have confirmed that agomelatine is approximately as effective as more commonly used antidepressants (e.g. SSRIs), but some qualified this as “marginally clinically relevant”, being only slightly above placebo. According to a 2013 review, agomelatine did not seem to provide an advantage in efficacy over other antidepressants for the acute-phase treatment of major depression.

Use in Special Populations

It is not recommended in Europe for use in children and adolescents below 18 years of age due to a lack of data on safety and efficacy. However, a study reported in September, 2020, showed greater efficacy vs. placebo for agomelatine 25mg per day in youth age 7-18 years. Only limited data is available on use in elderly people ≥ 75 years old with major depressive episodes.

It is not recommended during pregnancy or breastfeeding.

Contraindications

Agomelatine is contraindicated in patients with kidney or liver impairment. According to information disclosed by Servier in 2012, guidelines for the follow-up of patients treated with Valdoxan have been modified in concert with the European Medicines Agency. As some patients may experience increased levels of liver enzymes in their blood during treatment with Valdoxan, doctors have to run laboratory tests to check that the liver is working properly at the initiation of the treatment and then periodically during treatment, and subsequently decide whether to pursue the treatment or not. No relevant modification in agomelatine pharmacokinetic parameters in patients with severe renal impairment has been observed. However, only limited clinical data on its use in depressed patients with severe or moderate renal impairment with major depressive episodes is available. Therefore, caution should be exercised when prescribing agomelatine to these patients.

Adverse Effects

Agomelatine does not alter daytime vigilance and memory in healthy volunteers. In depressed patients, treatment with the drug increased slow wave sleep without modification of REM (Rapid Eye Movement) sleep amount or REM latency. Agomelatine also induced an advance of the time of sleep onset and of minimum heart rate. From the first week of treatment, onset of sleep and the quality of sleep were significantly improved without daytime clumsiness as assessed by patients.

Agomelatine appears to cause fewer sexual side effects and discontinuation effects than paroxetine.

  • Common (1-10% incidence) adverse effects include:
    • Hyperhidrosis (excess sweating that is not proportionate to the ambient temperature).
    • Abdominal pain.
    • Nausea.
    • Vomiting.
    • Diarrhoea.
    • Constipation.
    • Back pain.
    • Fatigue.
    • Increased ALAT and ASAT (liver enzymes).
    • Headache.
    • Dizziness.
    • Somnolence.
    • Insomnia.
    • Migraine.
    • Anxiety.
  • Uncommon (0.1-1%) adverse effects include:
    • Paraesthesia (abnormal sensations [e.g. itching, burning, tingling, etc.] due to malfunctioning of the peripheral nerves).
    • Blurred vision.
    • Eczema.
    • Pruritus (itching).
    • Urticaria.
    • Agitation.
    • Irritability.
    • Restlessness.
    • Aggression.
    • Nightmares.
    • Abnormal dreams.
  • Rare (0.01-0.1%) adverse effects include:
    • Mania.
    • Hypomania.
    • Suicidal ideation.
    • Suicidal behaviour.
    • Hallucinations.
    • Steatohepatitis.
    • Increased GGT and/or alkaline phosphatase.
    • Liver failure.
    • Jaundice.
    • Erythematous rash.
    • Face oedema and angioedema.
    • Weight gain or loss, which tends to be less significant than with SSRIs.

Dependence and Withdrawal

No dosage tapering is needed on treatment discontinuation. Agomelatine has no abuse potential as measured in healthy volunteer studies.

Overdose

Agomelatine is expected to be relatively safe in overdose.

Interactions

Agomelatine is a substrate of CYP1A2, CYP2C9 and CYP2C19. Inhibitors of these enzymes, e.g. the SSRI antidepressant fluvoxamine, reduce its clearance and can therefore lead to an increase in agomelatine exposure. There is also the potential for agomelatine to interact with alcohol to increase the risk of hepatotoxicity.

Pharmacology

Pharmacodynamics

Agomelatine is a melatonin receptor agonist (MT1 (Ki 0.1 nM) and MT2 (Ki = 0.12 nM)) and serotonin 5-HT2C (Ki = 631 nM) and 5-HT2B receptor (Ki = 660 nM) antagonist. Binding studies indicate that it has no effect on monoamine uptake and no affinity for adrenergic, histamine, cholinergic, dopamine, and benzodiazepine receptors, nor other serotonin receptors.

Agomelatine resynchronizes circadian rhythms in animal models of delayed sleep phase syndrome. By antagonising 5-HT2C, it disinhibits/increases noradrenaline and dopamine release specifically in the frontal cortex. Therefore, it is sometimes classified as a norepinephrine-dopamine disinhibitor. It has no influence on the extracellular levels of serotonin. Agomelatine has shown an antidepressant-like effect in animal models of depression (learned helplessness test, despair test, chronic mild stress) as well as in models with circadian rhythm desynchronisation and in models related to stress and anxiety. In humans, agomelatine has positive phase shifting properties; it induces a phase advance of sleep, body temperature decline and melatonin onset.

Antagonism of 5-HT2B is an antidepressant property agomelatine shares with several atypical antipsychotics, such as aripiprazole, which are themselves used as atypical antidepressants. 5-HT2B antagonists are currently being investigated for their usefulness in reducing cardiotoxicity of drugs as well as being effective in reducing headache. Hence this particular receptor antagonism of agomelatine is useful for its antidepressant effectiveness as well as reducing the drug’s adverse effects.

Chemistry

Structure

The chemical structure of agomelatine is very similar to that of melatonin. Where melatonin has an indole ring system, agomelatine has a naphthalene bioisostere instead.

Research

Agomelatine is under development by Servier for the treatment of generalised anxiety disorder and has reached phase III clinical trials for this indication, but in August 2017, Servier communicated that development for this indication is suspended.

Agomelatine is also studied for its effects on sleep regulation. Studies report various improvements in general quality of sleep metrics, as well as benefits in circadian rhythm disorders. It has been found more effective than placebo in the treatment of generalised anxiety disorder. A 2019 review suggested no recommendations of agomelatine in support of, or against, its use to treat individuals with seasonal affective disorder.

What is an Atypical Antipsychotic?

Published on by Andrew Marshall21 Comments

Introduction

The atypical antipsychotics (AAP), also known as second generation antipsychotics (SGAs) and serotonin-dopamine antagonists (SDAs), are a group of antipsychotic drugs (antipsychotic drugs in general are also known as major tranquilisers and neuroleptics, although the latter is usually reserved for the typical antipsychotics) largely introduced after the 1970s and used to treat psychiatric conditions.

Some atypical antipsychotics have received regulatory approval (e.g. by the Food and Drug Administration (FDA) of the US, the Therapeutic Goods Administration (TGA) of Australia, the Medical and Healthcare Products Regulatory Agency (MHRA) of the UK) for schizophrenia, bipolar disorder, autism, and as an adjunct in major depressive disorder.

Both generations of medication tend to block receptors in the brain’s dopamine pathways. Atypicals are less likely than haloperidol – the most widely used typical antipsychotic – to cause extrapyramidal motor control disabilities in patients such as unsteady Parkinson’s disease-type movements, body rigidity, and involuntary tremors. However, only a few of the atypicals have been demonstrated to be superior to lesser-used, low-potency first-generation antipsychotics in this regard.

As experience with these agents has grown, several studies have questioned the utility of broadly characterising antipsychotic drugs as “atypical/second generation” as opposed to “first generation,” noting that each agent has its own efficacy and side-effect profile. It has been argued that a more nuanced view in which the needs of individual patients are matched to the properties of individual drugs is more appropriate. Although atypical antipsychotics are thought to be safer than typical antipsychotics, they still have severe side effects, including tardive dyskinesia (a serious movement disorder), neuroleptic malignant syndrome, and increased risk of stroke, sudden cardiac death, blood clots, and diabetes. Significant weight gain may occur. Critics have argued that “the time has come to abandon the terms first-generation and second-generation antipsychotics, as they do not merit this distinction.”

Brief History

The first major tranquiliser or antipsychotic medication, chlorpromazine (Thorazine), a typical antipsychotic, was discovered in 1951 and introduced into clinical practice shortly thereafter. Clozapine (Clozaril), an atypical antipsychotic, fell out of favour due to concerns over drug-induced agranulocytosis. Following research indicating its effectiveness in treatment-resistant schizophrenia and the development of an adverse event monitoring system, clozapine re-emerged as a viable antipsychotic. According to Barker (2003), the three most-accepted atypical drugs are clozapine, risperidone, and olanzapine. However, he goes on to explain that clozapine is usually the last resort when other drugs fail. Clozapine can cause agranulocytosis (a decreased number of white blood cells), requiring blood monitoring for the patient. Despite the effectiveness of clozapine for treatment-resistant schizophrenia, agents with a more favourable side-effect profile were sought-after for widespread use. During the 1990s, olanzapine, risperidone, and quetiapine were introduced, with ziprasidone and aripiprazole following in the early 2000s. The atypical anti-psychotic paliperidone was approved by the FDA in late 2006.

The atypical antipsychotics have found favour among clinicians and are now considered to be first-line treatments for schizophrenia and are gradually replacing the typical antipsychotics. In the past, most researchers have agreed that the defining characteristics of atypical antipsychotics are the decreased incidence of extrapyramidal side effects (EPS) and an absence of sustained prolactin elevation.

The terminology can still be imprecise. The definition of “atypicality” was based upon the absence of extrapyramidal side effects, but there is now a clear understanding that atypical antipsychotics can still induce these effects (though to a lesser degree than typical antipsychotics). Recent literature focuses more upon specific pharmacological actions and less upon categorization of an agent as “typical” or “atypical”. There is no clear dividing line between the typical and atypical antipsychotics therefore categorisation based on the action is difficult.

More recent research is questioning the notion that second-generation antipsychotics are superior to first generation typical anti-psychotics. Using a number of parameters to assess quality of life, Manchester University researchers found that typical antipsychotics were no worse than atypical antipsychotics. The research was funded by the National Health Service (NHS) of the UK. Because each medication (whether first or second generation) has its own profile of desirable and adverse effects, a neuropsychopharmacologist may recommend one of the older (“typical” or first generation) or newer (“atypical” or second generation) antipsychotics alone or in combination with other medications, based on the symptom profile, response pattern, and adverse effects history of the individual patient.

Medical Uses

Atypical antipsychotics are typically used to treat schizophrenia or bipolar disorder. They are also frequently used to treat agitation associated with dementia, anxiety disorder, autism spectrum disorder, and obsessive-compulsive disorder (an off-label use). In dementia, they should only be considered after other treatments have failed and if the patient is a risk to themselves and/or others.

Schizophrenia

The first-line psychiatric treatment for schizophrenia is antipsychotic medication, which can reduce the positive symptoms of schizophrenia in about 8-15 days. Antipsychotics only appear to improve secondary negative symptoms of schizophrenia in the short term and may worsen negative symptoms overall. Overall there is no good evidence that atypical antipsychotics have any therapeutic benefit for treating the negative symptoms of schizophrenia.

There is very little evidence on which to base a risk and benefit assessment of using antipsychotics for long-term treatment.

The choice of which antipsychotic to use for a specific patient is based on benefits, risks, and costs. It is debatable whether, as a class, typical or atypical antipsychotics are better. Both have equal drop-out and symptom relapse rates when typicals are used at low to moderate dosages. There is a good response in 40-50% of patients, a partial response in 30-40%, and treatment resistance (failure of symptoms to respond satisfactorily after six weeks to two of three different antipsychotics) in the remaining 20%. Clozapine is considered a first choice treatment for treatment resistant schizophrenia, especially in the short term; in the longer-terms the risks of adverse effects complicate the choice. In turn, olanzapine, risperidone, and aripiprazole have been recommended for the treatment of first-episode psychosis.

Efficacy in the Treatment of Schizophrenia

The utility of broadly grouping the antipsychotics into first generation and atypical categories has been challenged. It has been argued that a more nuanced view, matching the properties of individual drugs to the needs of specific patients is preferable. While the atypical (second-generation) antipsychotics were marketed as offering greater efficacy in reducing psychotic symptoms while reducing side effects (and extrapyramidal symptoms in particular) than typical medications, the results showing these effects often lacked robustness, and the assumption was increasingly challenged even as atypical prescriptions were soaring. In 2005 the US government body NIMH (National Institute for Mental Health) published the results of a major independent (not funded by the pharmaceutical companies) multi-site, double-blind study (the CATIE project). This study compared several atypical antipsychotics to an older, mid-potency typical antipsychotic, perphenazine, among 1,493 persons with schizophrenia. The study found that only olanzapine outperformed perphenazine in discontinuation rate (the rate at which people stopped taking it due to its effects). The authors noted an apparent superior efficacy of olanzapine to the other drugs in terms of reduction in psychopathology and rate of hospitalizations, but olanzapine was associated with relatively severe metabolic effects such as a major weight gain problem (averaging 9.4 lbs over 18 months) and increases in glucose, cholesterol, and triglycerides. No other atypical studied (risperidone, quetiapine, and ziprasidone) did better than the typical perphenazine on the measures used, nor did they produce fewer adverse effects than the typical antipsychotic perphenazine (a result supported by a meta-analysis by Leucht et al. published in The Lancet), although more patients discontinued perphenazine owing to extrapyramidal effects compared to the atypical agents (8% vs. 2% to 4%, P=0.002). A phase 2 part of this CATIE study roughly replicated these findings. Compliance has not been shown to be different between the two types. Overall evaluations of the CATIE and other studies have led many researchers to question the first-line prescribing of atypicals over typicals, or even to question the distinction between the two classes.

It has been suggested that there is no validity to the term “second-generation antipsychotic drugs” and that the drugs that currently occupy this category are not identical to each other in mechanism, efficacy, and side-effect profiles.

Bipolar Disorder

In bipolar disorder, SGAs are most commonly used to rapidly control acute mania and mixed episodes, often in conjunction with mood stabilizers (which tend to have a delayed onset of action in such cases) such as lithium and valproate. In milder cases of mania or mixed episodes, mood stabiliser monotherapy may be attempted first. SGAs are also used to treat other aspects of the disorder (such as acute bipolar depression or as a prophylactic treatment) as adjuncts or as a monotherapy, depending on the drug. Both quetiapine and olanzapine have demonstrated significant efficacy in all three treatment phases of bipolar disorder. Lurasidone (trade name Latuda) has demonstrated some efficacy in the acute depressive phase of bipolar disorder.

Major Depressive Disorder

In non-psychotic major depressive disorder (MDD), some SGAs have demonstrated significant efficacy as adjunctive agents; and, such agents include:

  • Aripiprazole.
  • Brexpiprazole.
  • Olanzapine.
  • Quetiapine.
  • Ziprasidone.

Whereas only quetiapine has demonstrated efficacy as a monotherapy in non-psychotic MDD. Olanzapine/fluoxetine is an efficacious treatment in both psychotic and non-psychotic MDD.

Aripiprazole, brexpiprazole, olanzapine, and quetiapine have been approved as adjunct treatment for MDD by the FDA in the United States. Quetiapine and lurasidone have been approved, as monotherapies, for bipolar depression, but as of present, lurasidone has not been approved for MDD.

Autism

Both risperidone and aripiprazole have received FDA labelling for autism.

Dementia and Alzheimer’s Disease

Between May 2007 and April 2008, Dementia and Alzheimer’s together accounted for 28% of atypical antipsychotic use in patients aged 65 or older. The FDA requires that all atypical antipsychotics carry a black box warning that the medication has been associated with an increased risk of mortality in elderly patients. In 2005, the FDA issued an advisory warning of an increased risk of death when atypical antipsychotics are used in dementia. In the subsequent 5 years, the use of atypical antipsychotics to treat dementia decreased by nearly 50%.

Adverse Effects

The side effects reportedly associated with the various atypical antipsychotics vary and are medication-specific. Generally speaking, atypical antipsychotics are widely believed to have a lower likelihood for the development of tardive dyskinesia than the typical antipsychotics. However, tardive dyskinesia typically develops after long-term (possibly decades) use of antipsychotics. It is not clear if atypical antipsychotics, having been in use for a relatively short time, produce a lower incidence of tardive dyskinesia.

Some of the other side effects that have been suggested is that atypical antipsychotics increase the risk of cardiovascular disease. The research that Kabinoff et al. found that the increase in cardiovascular disease is seen regardless of the treatment they receive, instead it is caused by many different factors such as lifestyle or diet.

Sexual side effects have also been reported when taking atypical antipsychotics. In males antipsychotics reduce sexual interest, impair sexual performance with the main difficulties being failure to ejaculate. In females there may be abnormal menstrual cycles and infertility. In both males and females the breasts may become enlarged and a fluid will sometimes ooze from the nipples. Sexual adverse effects caused by some anti-psychotics are a result of an increase of prolactin. Sulpiride and Amisulpiride, as well as Risperdone and paliperidone (to a lesser extent) cause a high increase of prolactin.

In April 2005, the FDA issued an advisory and subsequent black box warning regarding the risks of atypical anti psychotic use among elderly patients with dementia. The FDA advisory was associated with decreases in the use of atypical antipsychotics, especially among elderly patients with dementia. Subsequent research reports confirmed the mortality risks associated with the use of both conventional and atypical antipsychotics to treat patients with dementia. Consequently, in 2008 the FDA issued although a black box warning for classical neuroleptics. Data on treatment efficacies are strongest for atypical antipsychotics. Adverse effects in patients with dementia include an increased risk of mortality and cerebrovascular events, as well as metabolic effects, extrapyramidal symptoms, falls, cognitive worsening, cardiac arrhythmia, and pneumonia. Conventional antipsychotics may pose an even greater safety risk. No clear efficacy evidence exists to support the use of alternative psychotropic classes (e.g. antidepressants, anticonvulsants).

Atypical antipsychotics may also cause anhedonia.

Drug-Induced OCD

Many different types of medication can create/induce pure OCD in patients that have never had symptoms before. A new chapter about OCD in the DSM-5 (2013) now specifically includes drug-induced OCD.

Atypical antipsychotics (second generation antipsychotics), such as olanzapine (Zyprexa), have been proven to induce de-novo OCD in patients.

Tardive Dyskinesia

All of the atypical antipsychotics warn about the possibility of tardive dyskinesia in their package inserts and in the PDR. It is not possible to truly know the risks of tardive dyskinesia when taking atypicals, because tardive dyskinesia can take many decades to develop and the atypical antipsychotics are not old enough to have been tested over a long enough period of time to determine all of the long-term risks. One hypothesis as to why atypicals have a lower risk of tardive dyskinesia is because they are much less fat-soluble than the typical antipsychotics and because they are readily released from D2 receptor and brain tissue. The typical antipsychotics remain attached to the D2 receptors and accumulate in the brain tissue which may lead to TD.

Both typical and atypical antipsychotics can cause tardive dyskinesia. According to one study, rates are lower with the atypicals at 3.9% per year as opposed to the typicals at 5.5% per year.

Metabolism

Recently, metabolic concerns have been of grave concern to clinicians, patients and the FDA. In 2003, the FDA required all manufacturers of atypical antipsychotics to change their labelling to include a warning about the risks of hyperglycaemia and diabetes with atypical antipsychotics. It must also be pointed out that although all atypicals must carry the warning on their labelling, some evidence shows that atypicals are not equal in their effects on weight and insulin sensitivity. The general consensus is that clozapine and olanzapine are associated with the greatest effects on weight gain and decreased insulin sensitivity, followed by risperidone and quetiapine. Ziprasidone and aripiprazole are thought to have the smallest effects on weight and insulin resistance, but clinical experience with these newer agents is not as developed as that with the older agents. The mechanism of these adverse effects is not completely understood but it is believed to result from a complex interaction between a number of pharmacologic actions of these drugs. Their effects on weight are believed to mostly derive from their actions on the H1 and 5-HT2C receptors, while their effects on insulin sensitivity are believed to be the result of a combination of their effects on body weight (as increased body mass is known to be a risk factor for insulin resistance) and their antagonistic effects on the M3receptor. Some of the newer agents, however, such as risperidone and its metabolite paliperidone, ziprasidone, lurasidone, aripiprazole, asenapine and iloperidone have clinically-insignificant effects on the M3 receptor and appear to carry a lower risk of insulin resistance. Whereas clozapine, olanzapine and quetiapine (indirectly via its active metabolite, norquetiapine) all antagonise the M3 receptor at therapeutic-relevant concentrations.

Recent evidence suggests a role of the α1 adrenoceptor and 5-HT2A receptor in the metabolic effects of atypical antipsychotics. The 5-HT2A receptor, however, is also believed to play a crucial role in the therapeutic advantages of atypical antipsychotics over their predecessors, the typical antipsychotics.

A study by Sernyak and colleagues found that the prevalence of diabetes in atypical antipsychotic treatments was statistically significantly higher than that of conventional treatment. The authors of this study suggest that it is a causal relationship the Kabinoff et al. suggest the findings only suggest a temporal association. Kabinoff et al. suggest that there is insufficient data from large studies to demonstrate a consistent or significant difference in the risk of insulin resistance during treatment with various atypical antipsychotics.

Discontinuation

The British National Formulary recommends a gradual withdrawal when discontinuing antipsychotics to avoid acute withdrawal syndrome or rapid relapse. Symptoms of withdrawal commonly include nausea, vomiting, and loss of appetite. Other symptoms may include restlessness, increased sweating, and trouble sleeping. Less commonly there may be a feeling of the world spinning, numbness, or muscle pains. Symptoms generally resolve after a short period of time.

There is tentative evidence that discontinuation of antipsychotics can result in psychosis. It may also result in reoccurrence of the condition that is being treated. Rarely tardive dyskinesia can occur when the medication is stopped.

Pharmacology

Pharmacodynamics

The atypical antipsychotics integrate with the serotonin (5-HT), norepinephrine (α, β), and dopamine (D) receptors in order to effectively treat schizophrenia.

D2 Receptor: Hyperactive dopaminergic activity on D2 receptors in the mesolimbic pathway is responsible for the positive symptoms of schizophrenia (hallucinations, delusions, paranoia). After taking an antipsychotic, antagonism of D2 receptors occurs throughout the entire brain, leading to a number of deleterious side effects from D2 receptor antagonism throughout the entire dopamine pathway system. Unfortunately, it’s not possible to affect D2 receptors only in the mesolimbic pathway. Fortunately, 5-HT2A receptor antagonism reverses these side effects to some extent. Reducing D2 dopaminergic activity in the mesolimbic pathway also results in an anhedonic effect, reducing pleasure, motivation, and the salience of one’s life experience. In the mesocortical pathway to the DLPFC and VMPFC, endogenous D2 receptor dopamine activity is sometimes low in schizophrenia, resulting in cognitive, affective, and, broadly, the negative symptoms of schizophrenia. D2 receptor antagonism here further compounds these problems. In the nigrostriatal pathway, D2 receptor antagonism results in extrapyramidal symptoms. If this antagonism occurs long enough, symptoms of EPS may become permanent, even if antipsychotic use is discontinued. In the tuberoinfundibular pathway, D2 receptor antagonism results in elevated prolactin. If prolactin levels become high enough, hyperprolactinaemia may occur, resulting in sexual dysfunction, weight gain, more rapid demineralisation of bones, and possibly galactorrhea and amenorrhea.

5-HT2A Receptor: When serotonin is released on to postsynaptic 5-HT2A receptors, the dopamine neuron is inhibited, thus acting as a brake on dopamine release. This brake is disrupted through action of a 5-HT2A antagonist, which disinhibits the dopamine neuron, stimulating dopamine release. The result of this is that dopamine competes with antipsychotic D2 antagonistic action at D2 receptors, thereby reducing antagonistic binding there and eliminating or lowering D2 antagonistic effects in several pathways of the dopamine system. In the nigrostratial pathway, it reduces EPS. In the tuberoinfundibular pathway, it reduces or eliminates prolactin elevation. Dopamine release in the mesolimbic pathway from 5-HT2A antagonism does not appear to be as robust as in the other pathways of the dopamine system, thereby accounting for why atypical antipsychotics still retain part of their efficacy against the positive symptoms of schizophrenia through their D2 antagonism. When 5-HT2A antagonistic agent particles occupy 5-HT2A receptors in the mesocortical pathway and in the prefrontal cortex, the negative symptoms of schizophrenia, affective symptoms, and cognitive deficits and abnormalities are treated and reduced. Furthermore, 5-HT2A receptor antagonism blocks the serotonergic excitation of cortical pyramidal cells, reducing glutamate release, which in turn lowers hyperactive dopaminergic D2 receptor activity in the mesolimbic pathway, reducing or eliminating the positive symptoms of schizophrenia.

Some effects of 5-HT1A receptor activation include decreased aggressive behaviour/ideation, increased sociability, and decreased anxiety and depression. 5-HT2C activation blocks dopamine and inhibits norepinephrine release. Blockade of the 5-HT2C receptor increases serotonin, releasing norepinephrine and dopamine within the brain. But neuronal reuptake of norepinephrine is limited sharply by some antipsychotics, for example ziprasidone. Increased norepinephrine can cause increased glucose levels, which is to say blood sugar levels. Increased blood sugar levels by increased norepinephrine causes hunger in many humans, which is why weight gain occurs with some antipsychotics if the norepinephrine is not inhibited. Inhibition of norepinephrine stabilises mood in humans. 5-HT6 receptor antagonists improve cognition, learning, and memory. The 5-HT7 receptor is very potent for the mitigation of bipolar conditions and also yields an antidepressant effect. The antipsychotics asenapine, lurasidone, risperidone, and aripiprazole are very potent at the 5-HT7 receptor. Antagonistic affinity for the H1 receptor also has an antidepressant effect. H1 antagonism blocks serotonin and norepinephrine reuptake. Patients with increased histamine levels have been observed to have lower serotonin levels. However, the H1 receptor is linked to weight gain. To have partial agonism at the 5-HT1A receptor can yield absence of weight gain in an antipsychotic. This is very relevant for ziprasidone, but it creates a risk for a prolonged QTc interval. On the other hand, blockade of the 5-HT3 receptor removes the risk for a prolonged QTc interval, but then creates a larger risk for weight gain. Relation to the 5-HT3 receptor increases caloric uptake and glucose, which is seen in clozapine and olanzapine. Other ways for dopamine to resolve is to have agonism at both the D2 receptor and 5-HT1A receptor, which normalises the dopamine level in the brain. This occurs with haloperidol and aripiprazole.

Whether the anhedonic, loss of pleasure and motivation effect resulting from dopamine insufficiency or blockade at D2 receptors in the mesolimbic pathway, which is mediated in some part by antipsychotics (and despite dopamine release in the mesocortical pathway from 5-HT2A antagonism, which is seen in atypical antipsychotics), or the positive mood, mood stabilisation, and cognitive improvement effect resulting from atypical antipsychotic serotonergic activity is greater for the overall quality of life effect of an atypical antipsychotic is a question that is variable between individual experience and the atypical antipsychotic(s) being used.

Terms

Inhibition. Disinhibition: The opposite process of inhibition, the turning on of a biological function. Release: Causes the appropriate neurotransmitters to be discharged in vesicles into the synapse where they attempt to bind to and activate a receptor. Downregulation and Upregulation.

Pharmacokinetics

Atypical antipsychotics are most commonly administered orally. Antipsychotics can also be injected, but this method is not as common. They are lipid-soluble, are readily absorbed from the digestive tract, and can easily pass the blood-brain barrier and placental barriers. Once in the brain, the antipsychotics work at the synapse by binding to the receptor. Antipsychotics are completely metabolised in the body and the metabolites are excreted in urine. These drugs have relatively long half-lives. Each drug has a different half-life, but the occupancy of the D2 receptor falls off within 24 hours with atypical antipsychotics, while lasting over 24 hours for the typical antipsychotics. This may explain why relapse into psychosis happens quicker with atypical antipsychotics than with typical antipsychotics, as the drug is excreted faster and is no longer working in the brain. Physical dependence with these drugs is very rare. However, if the drug is abruptly discontinued, psychotic symptoms, movement disorders, and sleep difficulty may be observed. It is possible that withdrawal is rarely seen because the AAP are stored in body fat tissues and slowly released.

Society and Culture

Between May 2007 and April 2008, 5.5 million Americans filled at least one prescription for an atypical antipsychotic. In patients under the age of 65, 71% of patients were prescribed an atypical antipsychotic to treat Schizophrenia or Bipolar Disorder where this dropped to 38% in patients aged 65 or above.

What is Bupropion?

Published on by Andrew Marshall13 Comments

Introduction

Bupropion, sold under the brand names Wellbutrin and Zyban among others, is an atypical antidepressant primarily used to treat major depressive disorder and to support smoking cessation. Bupropion is an effective antidepressant on its own, but it is also popular as an add-on medication in the cases of incomplete response to the first-line selective serotonin reuptake inhibitor (SSRI) antidepressant. Bupropion has several features that distinguish it from other antidepressants: it does not usually cause sexual dysfunction; it is not associated with weight gain and sleepiness, and it is more effective than SSRIs at improving symptoms of hypersomnia and fatigue.

Common adverse effects of bupropion with the greatest difference from placebo are dry mouth, nausea, constipation, insomnia, anxiety, tremor, and excessive sweating. Raised blood pressure is notable. Rare but serious side effects include seizure, liver toxicity, psychosis, and risk of overdose. Bupropion use during pregnancy may be associated with increased odds of congenital heart defects.

Bupropion acts as a norepinephrine-dopamine reuptake inhibitor and a nicotinic receptor antagonist. Chemically, it is an aminoketone that belongs to the class of substituted cathinones and more generally that of substituted amphetamines and substituted phenethylamines.

Bupropion was invented by Nariman Mehta, who worked at Burroughs Wellcome, in 1969. It was first approved for medical use in the United States in 1985. Bupropion was originally called by the generic name amfebutamone, before being renamed in 2000. In 2018, it was the 27th most commonly prescribed medication in the United States, with more than 24 million prescriptions.

Brief History

Bupropion was invented by Nariman Mehta of Burroughs Wellcome (now GlaxoSmithKline) in 1969, and the US patent for it was granted in 1974. It was approved by the US Food and Drug Administration (FDA) as an antidepressant on 30 December 1985, and marketed under the name Wellbutrin.[19][95] However, a significant incidence of seizures at the originally recommended dosage (400-600 mg/day) caused the withdrawal of the drug in 1986. Subsequently, the risk of seizures was found to be highly dose-dependent, and bupropion was re-introduced to the market in 1989 with a lower maximum recommended daily dose of 450 mg/day.

In 1996, the FDA approved a sustained-release formulation of alcohol-resistant bupropion called Wellbutrin SR, intended to be taken twice a day (as compared with three times a day for immediate-release Wellbutrin). In 2003, the FDA approved another sustained-release formulation called Wellbutrin XL, intended for once-daily dosing. Wellbutrin SR and XL are available in generic form in the United States and Canada. In 1997, bupropion was approved by the FDA for use as a smoking cessation aid under the name Zyban. In 2006, Wellbutrin XL was similarly approved as a treatment for seasonal affective disorder.

In France, marketing authorisation was granted for Zyban on 03 August 2001, with a maximum daily dose of 300 mg; only sustained-release bupropion is available, and only as a smoking cessation aid.

On 11 October 2007, two providers of consumer information on nutritional products and supplements, ConsumerLab.com and The People’s Pharmacy, released the results of comparative tests of different brands of bupropion. The People’s Pharmacy received multiple reports of increased side effects and decreased efficacy of generic bupropion, which prompted it to ask ConsumerLab.com to test the products in question. The tests showed that “one of a few generic versions of Wellbutrin XL 300 mg, sold as Budeprion XL 300 mg, didn’t perform the same as the brand-name pill in the lab.” The FDA investigated these complaints and concluded that Budeprion XL is equivalent to Wellbutrin XL in regard to bioavailability of bupropion and its main active metabolite hydroxybupropion. The FDA also said that coincidental natural mood variation is the most likely explanation for the apparent worsening of depression after the switch from Wellbutrin XL to Budeprion XL. On 03 October 2012, however, the FDA reversed this opinion, announcing that “Budeprion XL 300 mg fails to demonstrate therapeutic equivalence to Wellbutrin XL 300 mg.” The FDA did not test the bioequivalence of any of the other generic versions of Wellbutrin XL 300 mg, but requested that the four manufacturers submit data on this question to the FDA by March 2013. As of October 2013 the FDA has made determinations on the formulations from some manufacturers not being bioequivalent.

In April 2008, the FDA approved a formulation of bupropion as a hydrobromide salt instead of a hydrochloride salt, to be sold under the name Aplenzin by Sanofi-Aventis.

In 2009, the FDA issued a health advisory warning that the prescription of bupropion for smoking cessation has been associated with reports about unusual behaviour changes, agitation and hostility. Some people, according to the advisory, have become depressed or have had their depression worsen, have had thoughts about suicide or dying, or have attempted suicide. This advisory was based on a review of anti-smoking products that identified 75 reports of “suicidal adverse events” for bupropion over ten years. Based on the results of follow-up trials this warning was removed in 2016.

In 2012, the US Justice Department announced that GlaxoSmithKline had agreed to plead guilty and pay a $3-billion fine, in part for promoting the unapproved use of Wellbutrin for weight loss and sexual dysfunction.

In 2017, the European Medicines Agency recommended suspending a number of nationally approved medicines due to misrepresentation of bioequivalence study data by Micro Therapeutic Research Labs in India. The products recommended for suspension included several 300 mg modified-release Bupropion tablets.

Medical Uses

Depression

A majority of controlled clinical trials support efficacy of bupropion for the treatment of depression. However, the overall quality of the evidence is low, with one meta-analysis, for example, finding a small effect size of bupropion in depression and another finding a large effect size. Comparative head-to-head clinical trials indicate that bupropion is similar in response rate against depression to fluoxetine, sertraline, paroxetine, and venlafaxine; meanwhile remission rate tends to favour buproprion.

Given over the fall and winter months, bupropion prevents development of depression in those who suffer from recurring seasonal affective disorder: 15% of participants on bupropion experienced a major depressive episode vs 27% of those on placebo. Bupropion also improves depression in bipolar disorder, with the efficacy and risk of affective switch being similar to other antidepressants.

Bupropion has several features that distinguish it from other antidepressants: for instance, unlike the majority of antidepressants, it does not usually cause sexual dysfunction, and the occurrence of sexual side effects is not different from placebo. Bupropion treatment is not associated with weight gain; on the contrary, the majority of studies observed significant weight loss in bupropion-treated participants. Bupropion treatment also is not associated with the sleepiness that may be produced by other antidepressants. Bupropion is more effective than selective serotonin reuptake inhibitors (SSRIs) at improving symptoms of hypersomnia and fatigue in depressed patients. There appears to be a modest advantage for the SSRIs compared to bupropion in the treatment of depression with high anxiety; they are equivalent for the depression with moderate or low anxiety.

The addition of bupropion to a prescribed SSRI is a common strategy when people do not respond to the SSRI, and it is supported by clinical trials; however, it appears to be inferior to the addition of atypical antipsychotic aripiprazole.

Smoking Cessation

Prescribed as an aid for smoking cessation bupropion reduces the severity of craving for tobacco and withdrawal symptoms such as depressed mood, irritability, difficulty concentrating, and increased appetite. Initially, bupropion slows the weight gain that often occurs in the first weeks after quitting smoking. With time, however, this effect becomes negligible.

The bupropion treatment course lasts for seven to twelve weeks, with the patient halting the use of tobacco about ten days into the course. After the course, the effectiveness of bupropion for maintaining abstinence from smoking declines over time, from 37% of tobacco abstinence at 3 months to 20% at one year. It is unclear whether extending bupropion treatment helps to prevent relapse of smoking.

Overall, six months after the therapy, bupropion increases the likelihood of quitting smoking by approximately 1.6 fold as compared to placebo. In this respect, bupropion is as effective as nicotine replacement therapy but inferior to varenicline. Combining bupropion and nicotine replacement therapy does not improve the quitting rate.

In children and adolescents, the use of bupropion for smoking cessation does not appear to offer any significant benefits. The evidence for its use to aid smoking cessation in pregnant women is insufficient.

Attention Deficit Hyperactivity Disorder

The treatment of ADHD is not an approved indication of bupropion, and it is not mentioned in the current (2019) guideline on the ADHD treatment from the American Academy of Paediatrics. Systematic reviews of bupropion for the treatment of ADHD in both adults and children note that bupropion may be effective for ADHD but warn that this conclusion has to be interpreted with caution, because clinical trials were of low quality due to small sizes and risk of bias.

Sexual Dysfunction

Bupropion is less likely than other antidepressants to cause sexual dysfunction. A range of studies indicate that bupropion not only produces fewer sexual side effects than other antidepressants but can actually help to alleviate sexual dysfunction including sexual dysfunction induced by SSRI antidepressants. There have also been small studies suggesting that bupropion or a bupropion/trazodone combination may improve some measures of sexual function in women who have hypoactive sexual desire disorder (HSDD) and are not depressed. According to an expert consensus recommendation from the International Society for the Study of Women’s Sexual Health, bupropion can be considered as an off-label treatment for HSDD despite limited safety and efficacy data.

Obesity

Bupropion, when used for treating obesity over a period of 6 to 12 months, results in an average weight loss of 2.7 kg (5.9 lbs) over placebo. This is not much different from the weight loss produced by several other weight-loss medications such as sibutramine or orlistat. The combination drug naltrexone/bupropion has been approved by the US Food and Drug Administration (FDA) for the treatment of obesity.

Other Uses

Bupropion is not effective in the treatment of cocaine dependence, but it is showing promise in reducing drug use in light methamphetamine users. Based on studies indicating that bupropion lowers the level of the inflammatory mediator TNF-alpha, there have been suggestions that it might be useful in treating inflammatory bowel disease, psoriasis, and other autoimmune conditions, but very little clinical evidence is available. Bupropion is not effective in treating chronic low back pain.

Contraindications

The drug label advises that bupropion should not be prescribed to individuals with epilepsy or other conditions that lower the seizure threshold, such as anorexia nervosa, bulimia nervosa, benzodiazepine or alcohol withdrawal. It should be avoided in individuals who are taking monoamine oxidase inhibitors (MAOIs). When switching from MAOIs to bupropion, it is important to include a washout period of about two weeks between the medications. The label recommends that caution should be exercised when treating people with liver damage, severe kidney disease, and severe hypertension, and in children, adolescents and young adults due to the increased risk of suicidal ideation.

Side Effects

The common adverse effects of bupropion with the greatest difference from placebo are dry mouth, nausea, constipation, insomnia, anxiety, tremor, and excessive sweating. Bupropion has highest incidence of insomnia of all second-generation antidepressants, bar desvenlafaxine. It is also associated with about 20% increased risk of headache.

Bupropion raises systolic blood pressure by 6 mm Hg and the heart rate by 7 beats per minute. The prescribing information notes that hypertension, sometimes severe, is observed in some people taking bupropion, both with and without pre-existing hypertension. Safety of bupropion in people with cardiovascular conditions and its general cardiovascular safety profile remain unclear due to the lack of data.

Seizure is a rare but serious adverse effect of bupropion. It is strongly dose-dependent: for the immediate release preparation, the seizure incidence is 0.4% at the dose 300-450 mg per day; the incidence climbs almost ten-fold for the higher than recommended dose of 600 mg. For comparison, the incidence of unprovoked seizure in the general population is 0.07 to 0.09%, and the risk of seizure for a variety of other antidepressants is generally between 0 and 0.5% at the recommended doses.

Cases of liver toxicity leading to death or liver transplantation have been reported for bupropion. It is considered to be one of several antidepressants with greater risk of hepatotoxicity.

The prescribing information warns about bupropion triggering an angle-closure glaucoma attack. On the other hand, bupropion may decrease the risk of development of open angle glaucoma.

Bupropion use by mothers in the first trimester of pregnancy is associated with 23% increase of the odds in congenital heart defects in their children.

Psychiatric

The FDA requires all antidepressants, including bupropion, to carry a boxed warning stating that antidepressants may increase the risk of suicide in persons younger than 25. This warning is based on a statistical analysis conducted by the FDA which found a 2-fold increase in suicidal thought and behaviour in children and adolescents, and 1.5-fold increase in the 18-24 age group. For this analysis the FDA combined the results of 295 trials of 11 antidepressants in order to obtain statistically significant results. Considered in isolation, bupropion was not statistically different from placebo.

Bupropion prescribed for smoking cessation results in 25% increase of the risk of psychiatric side effects, in particular, anxiety (about 40% increase) and insomnia (about 80% increase). The evidence is insufficient to determine whether bupropion is associated with suicides or suicidal behaviour.

In rare cases, bupropion-induced psychosis may develop. It is associated with higher doses of bupropion; many cases described are at higher than recommended doses. Concurrent antipsychotic medication appears to be protective. In most cases the psychotic symptoms are eliminated by reducing the dose, ceasing treatment or adding antipsychotic medication.

Although studies are lacking, a handful of case reports suggest that abrupt discontinuation of bupropion may cause antidepressant discontinuation syndrome.

Overdose

Bupropion is considered moderately dangerous in overdose. According to an analysis of US National Poison Data System, adjusted for the number of prescriptions, bupropion and venlafaxine are the two new generation antidepressants (that is excluding tricyclic antidepressants) that result in the highest mortality and morbidity. For significant overdoses, seizures have been reported in about a third of all cases; other serious effects include hallucinations, loss of consciousness, and abnormal heart rhythms. When bupropion was one of several kinds of pills taken in an overdose, fever, muscle rigidity, muscle damage, hypertension or hypotension, stupor, coma, and respiratory failure have been reported. While most people recover, some people have died, and before they died suffered multiple uncontrolled seizures and heart attacks.

Interactions

Since bupropion is metabolised to hydroxybupropion by the enzyme CYP2B6, drug interactions with CYP2B6 inhibitors are possible: this includes such medications as paroxetine, sertraline, norfluoxetine (active metabolite of fluoxetine), diazepam, clopidogrel, and orphenadrine. The expected result is the increase of bupropion and decrease of hydroxybupropion blood concentration. The reverse effect (decrease of bupropion and increase of hydroxybupropion) can be expected with CYP2B6 inducers such as carbamazepine, clotrimazole, rifampicin, ritonavir, St John’s wort, and phenobarbital. Indeed, carbamazepine decreases exposure to bupropion by 90% and increases exposure to hydroxybupropion by 94%. Ritonavir, lopinavir/ritonavir, and efavirenz have been shown to decrease levels of bupropion and/or its metabolites. Ticlopidine and clopidogrel, both potent CYP2B6 inhibitors, have been found to considerably increase bupropion levels as well as decrease levels of its metabolite hydroxybupropion.

Bupropion and its metabolites are inhibitors of CYP2D6, with hydroxybupropion responsible for most of the inhibition. Additionally, bupropion and its metabolites may decrease expression of CYP2D6 in the liver. The end effect is a significant slowing of the clearance of other drugs metabolised by this enzyme. For instance, bupropion has been found to increase area-under-the-curve of desipramine, a CYP2D6 substrate, by 5-fold. Bupropion has also been found to increase levels of atomoxetine by 5.1-fold, while decreasing the exposure to its main metabolite by 1.5-fold. As another example, the ratio of dextromethorphan (a drug that is mainly metabolized by CYP2D6) to its major metabolite dextrorphan increased approximately 35-fold when it was administered to people being treated with 300 mg/day bupropion. When people on bupropion are given MDMA, about 30% increase of exposure to both drugs is observed, with enhanced mood but decreased heart rate effects of MDMA. Interactions with other CYP2D6 substrates, such as metoprolol, imipramine, nortriptyline, venlafaxine, and nebivolol have also been reported. However, in a notable exception, bupropion does not affect the concentrations of CYP2D6 substrates fluoxetine and paroxetine.

Bupropion lowers the seizure threshold, and therefore can potentially interact with other medications that also lower it, such as antipsychotics, tricyclic antidepressants, theophylline, and systemic corticosteroids. The prescribing information recommends minimising the use of alcohol, since in rare cases bupropion reduces alcohol tolerance.

Caution should be observed when combining bupropion with a monoamine oxidase inhibitor (MAOI), as it may result in hypertensive crisis.

Pharmacology

Pharmacodynamics and Mechanism of Action

The mechanism of action of bupropion is unclear but believed to be related to the fact that bupropion is a norepinephrine-dopamine reuptake inhibitor and antagonist of several nicotinic receptors. It is uncertain if it is a norepinephrine-dopamine releasing agent. Pharmacological actions of bupropion, to a significant degree, are due to its active metabolites hydroxybupropion, threo-hydrobupropion, and erythro-hydrobupropion that are present in the blood plasma at comparable or higher levels. Overall action of these metabolites, and particularly one enantiomer S,S-hydroxybupropion, is also characterised by inhibition of norepinephrine and dopamine reuptake and nicotinic antagonism. The occupancy of dopamine transporter (DAT) by bupropion and its metabolites in the human brain as measured by positron emission tomography is 6-35%.

Bupropion also weakly inhibits the α1 adrenergic receptor, with IC50 of 16μM.

Pharmacokinetics

After oral administration, bupropion is rapidly and completely absorbed reaching the peak blood plasma concentration after 1.5 hours (tmax). Sustained release (SR) and extended release (XL) formulations have been designed to slow down absorption resulting in tmax of 3 hours and 5 hours, respectively. Absolute bioavailability of bupropion is unknown but is presumed to be low, at 5-20%, due to the first-pass metabolism. As for the relative biovailability of the formulations, XL formulation has lower bioavailability (68%) compared to SR formulation and immediate release bupropion.

Bupropion is metabolized in the body by a variety of pathways. The oxidative pathways are by cytochrome P450 isoenzymes CYP2B6 leading to R,R- and S,S-hydroxybupropion and, to a lesser degree, CYP2C19 leading to 4′-hydroxybupropion. The reductive pathways are by 11β-hydroxysteroid dehydrogenase type 1 in the liver and AKR7A2/AKR7A3 in the intestine leading to threo-hydrobupropion and by yet unknown enzyme leading to erythro-hydrobupropion.

The metabolism of bupropion is highly variable: the effective doses of bupropion received by persons who ingest the same amount of the drug may differ by as much as 5.5 times (with a half-life of 12-30 hours), while the effective doses of hydroxybupropion may differ by as much as 7.5 times (with a half-life of 15-25 hours). Based on this, some researchers have advocated monitoring of the blood level of bupropion and hydroxybupropion.

Chemistry

Bupropion is an aminoketone that belongs to the class of substituted cathinones and the more general class of substituted phenethylamines. The clinically used bupropion is racemic, that is a mixture of two enantiomers: S-bupropion and R-bupropion. Although the optical isomers on bupropion can be separated, they rapidly racemize under physiological conditions.

There have been reported cases of false-positive urine amphetamine tests in persons taking bupropion.

Synthesis

It is synthesized in two chemical steps starting from 3′-chloro-propiophenone. The alpha position adjacent to the ketone is first brominated followed by nucleophilic displacement of the resulting alpha-bromoketone with t-butylamine and treated with hydrochloric acid to give bupropion as the hydrochloride salt in 75-85% overall yield.

Society and Culture

Recreational Use

While bupropion demonstrates some potential for misuse, this potential is less than of other commonly used stimulants, being limited by features of bupropion’s pharmacology. Bupropion misuse is uncommon. There have been a number of anecdotal and case-study reports of bupropion abuse, but the bulk of evidence indicates that the subjective effects of bupropion via the oral route are markedly different from those of addictive stimulants such as cocaine or amphetamine. That said, bupropion, via non-conventional routes of administration (e.g. injection, insufflation), is reported to be abused in the United States and Canada, notably in prisons.

Legal Status

In Russia bupropion is banned as a narcotic drug, yet not per se but rather as a derivative of methcathinone. In Australia and the UK, smoking cessation is the only licensed use of bupropion.