What is a Psycholeptic?

Introduction

In pharmacology, a psycholeptic is a medication which produces a calming effect upon a person.

Refer to Analeptic.

Background

Such medications include barbiturates, benzodiazepines, nonbenzodiazepines, phenothiazines, opiates/opioids, carbamates, ethanol, 2-methyl-2-butanol, cannabinoids (in some classifications), some antidepressants, neuroleptics, and some anticonvulsants.

Many herbal medicines may also be classified as psycholeptics (e.g. kava).

Psycholeptics are classified under N05 in the Anatomical Therapeutic Chemical Classification System.

What is Halazepam?

Introduction

Halazepam is a benzodiazepine derivative that was marketed under the brand names Paxipam in the United States, Alapryl in Spain, and Pacinone in Portugal.

Medical Uses

Halazepam was used for the treatment of anxiety.

Adverse Effects

Adverse effects include drowsiness, confusion, dizziness, and sedation. Gastrointestinal side effects have also been reported including dry mouth and nausea.

Pharmacokinetics and Pharmacodynamics

Pharmacokinetics and pharmacodynamics were listed in Current Psychotherapeutic Drugs published on 15 June 1998 as follows:

  • Onset of action: Intermediate to slow.
  • Plasma half life: 14 hours for parent drug and 30-100 hours for its metabolite.
  • Peak plasma levels: 1-3 hours for parent drug and 3-6 hours for its metabolite.
  • Metabolism: Metabolised into desmethyldiazepam and 3-hydroxyhalazepam (in the liver).
  • Excretion: Excreted through kidneys.
  • Protein binding: 98% bound to plasma protein.

Regulatory Information

Halazepam is classified as a schedule 4 controlled substance with a corresponding code 2762 by the Drug Enforcement Administration (DEA).

Commercial Production

Halazepam was invented by Schlesinger Walter in the US. It was marketed as an anti-anxiety agent in 1981. However, Halazepam is not commercially available in the United States because it was withdrawn by its manufacturer for poor sales.

What is Loprazolam?

Introduction

Loprazolam (triazulenone) marketed under many brand names is a benzodiazepine medication.

It possesses anxiolytic, anticonvulsant, hypnotic, sedative and skeletal muscle relaxant properties. It is licensed and marketed for the short-term treatment of moderately-severe insomnia.

It was patented in 1975 and came into medical use in 1983.

Medical Uses

Insomnia can be described as a difficulty falling asleep, frequent awakening, early awakenings or a combination of each. Loprazolam is a short-acting benzodiazepine and is sometimes used in patients who have difficulty in maintaining sleep or have difficulty falling asleep. Hypnotics should only be used on a short-term basis or in those with chronic insomnia on an occasional basis.

Dose

The dose of loprazolam for insomnia is usually 1 mg but can be increased to 2 mg if necessary. In the elderly a lower dose is recommended due to more pronounced effects and a significant impairment of standing up to 11 hours after dosing of 1 mg of loprazolam. The half-life is much more prolonged in the elderly than in younger patients. A half-life of 19.8 hours has been reported in elderly patients. Patients and prescribing physicians should, however, bear in mind that higher doses of loprazolam may impair long-term memory functions.

Side Effects

Side effects of loprazolam are generally the same as for other benzodiazepines such as diazepam.[5] The most significant difference in side effects of loprazolam and diazepam is it is less prone to day time sedation as the half-life of loprazolam is considered to be intermediate whereas diazepam has a very long half-life. The side effects of loprazolam are the following:

  • Drowsiness.
  • Paradoxical increase in aggression.
  • Lightheadedness.
  • Confusion.
  • Muscle weakness.
  • Ataxia (particularly in the elderly).
  • Amnesia.
  • Headache.
  • Vertigo.
  • Hypotension.
  • Salivation changes.
  • Gastro-intestinal disturbances.
  • Visual disturbances.
  • Dysarthria.
  • Tremor.
  • Changes in libido.
  • Incontinence.
  • Urinary retention.
  • Blood disorders and jaundice.
  • Skin reactions.
  • Dependence and withdrawal reactions.

Residual ‘hangover’ effects after night-time administration of loprazolam such as sleepiness, impaired psychomotor and cognitive functions may persist into the next day which may increase risks of falls and hip fractures.

Tolerance, Dependence and Withdrawal

Loprazolam, like all other benzodiazepines, is recommended only for the short-term management of insomnia in the UK, owing to the risk of serious adverse effects such as tolerance, dependence and withdrawal, as well as adverse effects on mood and cognition. Benzodiazepines can become less effective over time, and patients can develop increasing physical and psychological adverse effects, e.g. agoraphobia, gastrointestinal complaints, and peripheral nerve abnormalities such as burning and tingling sensations.

Loprazolam has a low risk of physical dependence and withdrawal if it is used for less than 4 weeks or very occasionally. However, one placebo-controlled study comparing 3 weeks of treatment for insomnia with either loprazolam or triazolam showed rebound anxiety and insomnia occurring 3 days after discontinuing loprazolam therapy, whereas with triazolam the rebound anxiety and insomnia was seen the next day. The differences between the two are likely due to the differing elimination half-lives of the two drugs. These results would suggest that loprazolam and possibly other benzodiazepines should be prescribed for 1-2 weeks rather than 2-4 weeks to reduce the risk of physical dependence, withdrawal, and rebound phenomenon.

Withdrawal Symptoms

Slow reduction of the dosage over a period of months at a rate that the individual can tolerate greatly minimises the severity of the withdrawal symptoms. Individuals who are benzodiazepine dependent often cross to an equivalent dose of diazepam to taper gradually, as diazepam has a longer half-life and small dose reductions can be achieved more easily.

  • Anxiety and panic attacks.
  • Sweating.
  • Nightmares.
  • Insomnia.
  • Headache.
  • Tremor.
  • Nausea and vomiting.
  • Feelings of unreality.
  • Abnormal sensation of movement.
  • Hypersensitivity to stimuli.
  • Hyperventilation.
  • Flushing.
  • Sweating.
  • Palpitations.
  • Dimensional distortions of rooms and television pictures.
  • Paranoid thoughts and feelings of persecution.
  • Depersonalisation.
  • Fears of going mad.
  • Heightened perception of taste, smell, sound, and light; photophobia.
  • Agoraphobia.
  • Clinical depression.
  • Poor memory and concentration.
  • Aggression.
  • Excitability.
  • Somatic symptoms.
  • Numbness.
  • Altered sensations of the skin.
  • Pain.
  • Stiffness.
  • Weakness in the neck, head, jaw, and limbs.
  • Muscle fasciculation, ranging from twitches to jerks, affecting the legs or shoulders.
  • Ataxia.
  • Paraesthesia.
  • Influenza-like symptoms.
  • Blurred double vision.
  • Menorrhagia.
  • Loss of or dramatic gain in appetite.
  • Thirst with polyuria.
  • Urinary incontinence.
  • Dysphagia.
  • Abdominal pain.
  • Diarrhoea.
  • Constipation.

Major complications can occur after abrupt or rapid withdrawal, especially from high doses, producing symptoms such as:

  • Psychosis.
  • Confusion.
  • Visual and auditory hallucinations.
  • Delusions.
  • Epileptic seizures (which may be fatal).
  • Suicidal thoughts or actions.
  • Abnormal, often severe, drug seeking behaviour.

It has been estimated that between 30% and 50% of long-term users of benzodiazepines will experience withdrawal symptoms. However, up to 90% of patients withdrawing from benzodiazepines experienced withdrawal symptoms in one study, but the rate of taper was very fast at 25% of dose per week. Withdrawal symptoms tend to last between 3 weeks to 3 months, although 10-15% of people may experience a protracted benzodiazepine withdrawal syndrome with symptoms persisting and gradually declining over a period of many months and occasionally several years.

Contraindications and Special Caution

Benzodiazepines require special precaution if used in the elderly, during pregnancy, in children, alcohol or drug-dependent individuals and individuals with comorbid psychiatric disorders. Loprazolam, similar to other benzodiazepines and nonbenzodiazepine hypnotic drugs causes impairments in body balance and standing steadiness in individuals who wake up at night or the next morning. Falls and hip fractures are frequently reported. The combination with alcohol increases these impairments. Partial, but incomplete tolerance develops to these impairments.

Mechanism of Action

Loprazolam is a benzodiazepine, which acts via positively modulating the GABAA receptor complex via a binding to the benzodiazepine receptor which is situated on alpha subunit containing GABAA receptors. This action enhances the effect of the neurotransmitter GABA on the GABAA receptor complex by increasing the opening frequency of the chloride ion channel. This action allows more chloride ions to enter the neuron which in turn produces such effects as; muscle relaxation, anxiolytic, hypnotic, amnesic and anticonvulsant action. These properties can be used for therapeutic benefit in clinical practice. These properties are also sometimes used for recreational purposes in the form of drug abuse of benzodiazepines where high doses are used to achieve intoxication and or sedation.

Pharmacokinetics

After oral administration of loprazolam on an empty stomach, it takes 2 hours for serum concentration levels to peak, significantly longer than other benzodiazepine hypnotics. This delay brings into question the benefit of loprazolam for the treatment of insomnia when compared to other hypnotics (particularly when the major complaint is difficulty falling asleep instead of difficulty maintaining sleep for the entire night), although some studies show that loprazolam may induce sleep within half an hour, indicating rapid penetration into the brain. The peak plasma delay of loprazolam, therefore, may not be relevant to loprazolam’s efficacy as a hypnotic. If taken after a meal it can take even longer for loprazolam plasma levels to peak and peak levels may be lower than normal. Loprazolam significantly alters electrical activity in the brain as measured by EEG, with these changes becoming more pronounced as the dose increases. Roughly half of each dose is metabolized in humans to produce an active metabolite, (a piperazine with lesser potency), the other half is excreted unchanged. The half-life of the active metabolite is about the same as the parent compound loprazolam.

What is the Beers Criteria?

Introduction

The Beers Criteria for Potentially Inappropriate Medication Use in Older Adults, commonly called the Beers List, are guidelines for healthcare professionals to help improve the safety of prescribing medications for older adults 65 years and older in all except palliative setting.

They emphasize deprescribing medications that are unnecessary, which helps to reduce the problems of polypharmacy, drug interactions, and adverse drug reactions, thereby improving the risk–benefit ratio of medication regimens in at-risk people.

The criteria are used in geriatrics clinical care to monitor and improve the quality of care. They are also used in training, research, and healthcare policy to assist in developing performance measures and document outcomes. These criteria include lists of medications in which the potential risks may be greater than the potential benefits for people 65 and older. By considering this information, practitioners may be able to reduce harmful side effects caused by such medications. The Beers Criteria are intended to serve as a guide for clinicians and not as a substitute for professional judgement in prescribing decisions. The criteria may be used in conjunction with other information to guide clinicians about safe prescribing in older adults.

Brief History

Geriatrician Mark H. Beers formulated the Beers Criteria through a consensus panel of experts using the Delphi method. The criteria were originally published in the Archives of Internal Medicine in 1991 and updated in 1997, 2003, 2012, 2015, and most recently in January 2019.

In 2018, the American Geriatrics Society (AGS) partnered with CSIS Health Corp to provide the first and only licensed software application of the Beers Criteria for use in Electronic Health Records, Population Health Management, and Care Management platforms.

Management of Criteria

In 2011, the AGS convened an eleven-member multidisciplinary panel of experts in geriatric medicine, nursing, and pharmacotherapy to develop the 2012 edition of the AGS Updated Beers Criteria for Potentially Inappropriate Medication Use in Older Adults.

The 2012 AGS Beers Criteria differ from previous editions in several ways. In addition to using a modified Delphi process for building consensus, the expert panel followed the evidence-based approach that AGS has used since it developed its first practice guideline on persistent pain in 1998. The Institute of Medicine (IOM) in its 2011 report, Clinical Practice Guidelines We Can Trust, recommended that all guideline developers complete a systematic review of the evidence. Following the recommendation of the IOM, AGS added a public comment period that occurred in parallel to its standard invited external peer review process. In a significant departure from previous versions of the criteria, each recommendation is rated for quality of both the evidence supporting the panel’s recommendations and the strength of their recommendations.

In another departure from the 2003 criteria, the 2012 AGS Beers Criteria identify and group medications that may be inappropriate for older adults into three different categories instead of the previous two. The first category includes medications that are potentially inappropriate for older people because they either pose high risks of adverse effects or appear to have limited effectiveness in older patients, and because there are alternatives to these medications. The second category includes medications that are potentially inappropriate for older people who have certain diseases or disorders because these drugs may exacerbate the specified health problems. The third category includes medications that, although they may be associated with more risks than benefits in general, may be the best choice for a particular individual if administered with caution.

The 2012 AGS Beers Criteria was released in February 2012 via publication in the early online edition of the Journal of the American Geriatrics Society.

The most recent update to the Beers criteria was completed in 2019.

Style of the Publication

Drugs listed on the Beers List are categorised according to risks for negative outcomes. The tables include medications that have cautions, should be avoided, should be avoided with concomitant medical conditions, and are contraindicated and relatively contraindicated in the elderly population. An example of an included drug is diphenhydramine (Benadryl), a first-generation H1 antagonist with anticholinergic properties, which may increase sedation and lead to confusion or falls.

What is Imipramine?

Introduction

Imipramine, sold under the brand name Tofranil, among others, is a tricyclic antidepressant (TCA) mainly used in the treatment of depression.

It is also effective in treating anxiety and panic disorder. The drug is also used to treat bedwetting. Imipramine is taken by mouth.

Common side effects of imipramine include dry mouth, drowsiness, dizziness, low blood pressure, rapid heart rate, urinary retention, and electrocardiogram changes. Overdose of the medication can result in death. Imipramine appears to work by increasing levels of serotonin and norepinephrine and by blocking certain serotonin, adrenergic, histamine, and cholinergic receptors.

Imipramine was discovered in 1951 and was introduced for medical use in 1957. It was the first TCA to be marketed. Imipramine and the other TCAs have decreased in use in recent decades, due to the introduction of the selective serotonin reuptake inhibitors (SSRIs), which have fewer side effects and are safer in overdose.

Brief History

The parent compound of imipramine, 10,11-dihydro-5H-dibenz[b,f]azepine (dibenzazepine), was first synthesized in 1899, but no pharmacological assessment of this compound or any substituted derivatives was undertaken until the late 1940s. Imipramine was first synthesized in 1951, as an antihistamine. The antipsychotic effects of chlorpromazine were discovered in 1952, and imipramine was then developed and studied as an antipsychotic for use in patients with schizophrenia. The medication was tested in several hundred patients with psychosis, but showed little effectiveness. However, imipramine was serendipitously found to possess antidepressant effects in the mid-1950s following a case report of symptom improvement in a woman with severe depression who had been treated with it. This was followed by similar observations in other patients and further clinical research. Subsequently, imipramine was introduced for the treatment of depression in Europe in 1958 and in the United States in 1959. Along with the discovery and introduction of the monoamine oxidase inhibitor iproniazid as an antidepressant around the same time, imipramine resulted in the establishment of monoaminergic drugs as antidepressants.

In the late 1950s, imipramine was the first TCA to be developed (by Ciba). At the first international congress of neuropharmacology in Rome, September 1958 Dr Freyhan from the University of Pennsylvania discussed as one of the first clinicians the effects of imipramine in a group of 46 patients, most of them diagnosed as “depressive psychosis”. The patients were selected for this study based on symptoms such as depressive apathy, kinetic retardation and feelings of hopelessness and despair. In 30% of all patients, he reported optimal results, and in around 20%, failure. The side effects noted were atropine-like, and most patients suffered from dizziness. Imipramine was first tried against psychotic disorders such as schizophrenia, but proved ineffective. As an antidepressant, it did well in clinical studies and it is known to work well in even the most severe cases of depression. It is not surprising, therefore, that imipramine may cause a high rate of manic and hypomanic reactions in hospitalised patients with pre-existing bipolar disorder, with one study showing that up to 25% of such patients maintained on Imipramine switched into mania or hypomania. Such powerful antidepressant properties have made it favourable in the treatment of treatment-resistant depression.

Before the advent of SSRIs, its sometimes intolerable side-effect profile was considered more tolerable. Therefore, it became extensively used as a standard antidepressant and later served as a prototypical drug for the development of the later-released TCAs. Since the 1990s, it has no longer been used as commonly, but is sometimes still prescribed as a second-line treatment for treating major depression . It has also seen limited use in the treatment of migraines, ADHD, and post-concussive syndrome. Imipramine has additional indications for the treatment of panic attacks, chronic pain, and Kleine-Levin syndrome. In paediatric patients, it is relatively frequently used to treat pavor nocturnus and nocturnal enuresis.

Medical Uses

Imipramine is used in the treatment of depression and certain anxiety disorders. It is similar in efficacy to the antidepressant drug moclobemide. It has also been used to treat nocturnal enuresis because of its ability to shorten the time of delta wave stage sleep, where wetting occurs. In veterinary medicine, imipramine is used with xylazine to induce pharmacologic ejaculation in stallions. Blood levels between 150-250 ng/mL of imipramine plus its metabolite desipramine generally correspond to antidepressant efficacy.

Available Forms

Imipramine is available in the form of oral tablets and capsules.

Contraindications

Combining it with alcohol consumption causes excessive drowsiness. It may be unsafe during pregnancy.

Side Effects

Those listed in italics below denote common side effects.

  • Central nervous system: dizziness, drowsiness, confusion, seizures, headache, anxiety, tremors, stimulation, weakness, insomnia, nightmares, extrapyramidal symptoms in geriatric patients, increased psychiatric symptoms, paraesthesia.
  • Cardiovascular: orthostatic hypotension, ECG changes, tachycardia, hypertension, palpitations, dysrhythmias
  • Eyes, ears, nose and throat: blurred vision, tinnitus, mydriasis.
  • Gastrointestinal: dry mouth, nausea, vomiting, paralytic ileus, increased appetite, cramps, epigastric distress, jaundice, hepatitis, stomatitis, constipation, taste change.
  • Genitourinary: urinary retention.
  • Hematological: agranulocytosis, thrombocytopenia, eosinophilia, leukopenia.
  • Skin: rash, urticaria, diaphoresis, pruritus, photosensitivity.

Overdose

Refer to Tricyclic Antidepressant Overdose.

Pharmacology

Pharmacodynamics

Imipramine affects numerous neurotransmitter systems known to be involved in the aetiology of depression, anxiety, attention-deficit hyperactivity disorder (ADHD), enuresis and numerous other mental and physical conditions. Imipramine is similar in structure to some muscle relaxants, and has a significant analgesic effect and, thus, is very useful in some pain conditions.

The mechanisms of imipramine’s actions include, but are not limited to, effects on:

  • Serotonin: very strong reuptake inhibition.
  • Norepinephrine: strong reuptake inhibition.
    • Desipramine has more affinity to norepinephrine transporter than imipramine.
  • Dopamine:
    • Imipramine blocks D2 receptors.
    • Imipramine, and its metabolite desipramine, have no appreciable affinity for the dopamine transporter (Ki = 8,500 and >10,000 nM, respectively).
  • Acetylcholine:
    • Imipramine is an anticholinergic, specifically an antagonist of the muscarinic acetylcholine receptors.
    • Thus, it is prescribed with caution to the elderly and with extreme caution to those with psychosis, as the general brain activity enhancement in combination with the “dementing” effects of anticholinergics increases the potential of imipramine to cause hallucinations, confusion and delirium in this population.
  • Epinephrine:
    • Imipramine antagonises adrenergic receptors, thus sometimes causing orthostatic hypotension.
  • Sigma receptor:
    • Activity on sigma receptors is present, but it is very weak (Ki = 520 nM) and it is about half that of amitriptyline (Ki = 300 nM).
  • Histamine:
    • Imipramine is an antagonist of the histamine H1 receptors.
  • BDNF:
    • BDNF is implicated in neurogenesis in the hippocampus, and studies suggest that depressed patients have decreased levels of BDNF and reduced hippocampal neurogenesis.
    • It is not clear how neurogenesis restores mood, as ablation of hippocampal neurogenesis in murine models do not show anxiety related or depression related behaviours.
    • Chronic imipramine administration results in increased histone acetylation (which is associated with transcriptional activation and decondensed chromatin) at the hippocampal BDNF promoter, and also reduced expression of hippocampal HDAC5.

Pharmacokinetics

Within the body, imipramine is converted into desipramine (desmethylimipramine) as a metabolite.

Chemistry

Imipramine is a tricyclic compound, specifically a dibenzazepine, and possesses three rings fused together with a side chain attached in its chemical structure. Other dibenzazepine TCAs include desipramine (N-desmethylimipramine), clomipramine (3-chloroimipramine), trimipramine (2′-methylimipramine or β-methylimipramine), and lofepramine (N-(4-chlorobenzoylmethyl)desipramine). Imipramine is a tertiary amine TCA, with its side chain-demethylated metabolite desipramine being a secondary amine. Other tertiary amine TCAs include amitriptyline, clomipramine, dosulepin (dothiepin), doxepin, and trimipramine. The chemical name of imipramine is 3-(10,11-dihydro-5H-dibenzo[b,f]azepin-5-yl)-N,N-dimethylpropan-1-amine and its free base form has a chemical formula of C19H24N2 with a molecular weight of 280.407 g/mol. The drug is used commercially mostly as the hydrochloride salt; the embonate (pamoate) salt is used for intramuscular administration and the free base form is not used. The CAS Registry Number of the free base is 50-49-7, of the hydrochloride is 113-52-0, and of the embonate is 10075-24-8.

Society and Culture

Generic Names

Imipramine is the English and French generic name of the drug and its INN, BAN, and DCF, while imipramine hydrochloride is its USAN, USP, BANM, and JAN. Its generic name in Spanish and Italian and its DCIT are imipramina, in German is imipramin, and in Latin is imipraminum. The embonate salt is known as imipramine pamoate.

Brand Names

Imipramine is marketed throughout the world mainly under the brand name Tofranil. Imipramine pamoate is marketed under the brand name Tofranil-PM for intramuscular injection.

Availability

Imipramine is available for medical use widely throughout the world, including in the United States, the United Kingdom, elsewhere in Europe, Brazil, South Africa, Australia, and New Zealand.

What is Neuroleptic Malignant Syndrome?

Introduction

Neuroleptic malignant syndrome (NMS) is a rare but life-threatening reaction that can occur in response to neuroleptic or antipsychotic medication. Symptoms include high fever, confusion, rigid muscles, variable blood pressure, sweating, and fast heart rate. Complications may include rhabdomyolysis, high blood potassium, kidney failure, or seizures.

Any medications within the family of neuroleptics can cause the condition, though typical antipsychotics appear to have a higher risk than atypicals, specifically first generation antipsychotics like haloperidol. Onset is often within a few weeks of starting the medication but can occur at any time. Risk factors include dehydration, agitation, and catatonia.

Rapidly decreasing the use of levodopa or other dopamine agonists, such as pramipexole, may also trigger the condition. The underlying mechanism involves blockage of dopamine receptors. Diagnosis is based on symptoms.

Management includes stopping the offending medication, rapid cooling, and starting other medications. Medications used include dantrolene, bromocriptine, and diazepam. The risk of death among those affected is about 10%. Rapid diagnosis and treatment is required to improve outcomes. Many people can eventually be restarted on a lower dose of antipsychotic.

As of 2011, among those in psychiatric hospitals on neuroleptics about 15 per 100,000 are affected per year (0.015%). In the second half of the 20th century rates were over 100 times higher at about 2% (2,000 per 100,000). Males appear to be more often affected than females. The condition was first described in 1956.

Brief History

NMS was known about as early as 1956, shortly after the introduction of the first phenothiazines. NMS was first described in 1960 by French clinicians who had been working on a study involving haloperidol. They characterized the condition that was associated with the side effects of haloperidol “syndrome malin des neuroleptiques”, which was translated to neuroleptic malignant syndrome.

Signs and Symptoms

The first symptoms of neuroleptic malignant syndrome are usually muscle cramps and tremors, fever, symptoms of autonomic nervous system instability such as unstable blood pressure, and sudden changes in mental status (agitation, delirium, or coma). Once symptoms appear, they may progress rapidly and reach peak intensity in as little as three days. These symptoms can last anywhere from eight hours to forty days.

Symptoms are sometimes misinterpreted by doctors as symptoms of mental illness which can result in delayed treatment. NMS is less likely if a person has previously been stable for a period of time on antipsychotics, especially in situations where the dose has not been changed and there are no issues of noncompliance or consumption of psychoactive substances known to worsen psychosis.

  • Increased body temperature >38 °C (>100.4 °F);
  • Confused or altered consciousness;
  • sweating;
  • Rigid muscles; and/or
  • Autonomic imbalance.

Causes

NMS is usually caused by antipsychotic drug use, and a wide range of drugs can result in NMS. Individuals using butyrophenones (such as haloperidol and droperidol) or phenothiazines (such as promethazine and chlorpromazine) are reported to be at greatest risk. However, various atypical antipsychotics such as clozapine, olanzapine, risperidone, quetiapine, and ziprasidone have also been implicated in cases.

NMS may also occur in people taking dopaminergic drugs (such as levodopa) for Parkinson’s disease, most often when the drug dosage is abruptly reduced. In addition, other drugs with anti-dopaminergic activity, such as the antiemetic metoclopramide, can induce NMS. Tetracyclics with anti-dopaminergic activity have been linked to NMS in case reports, such as the amoxapines. Additionally, desipramine, dothiepin, phenelzine, tetrabenazine, and reserpine have been known to trigger NMS. Whether lithium can cause NMS is unclear.

At the molecular level, NMS is caused by a sudden, marked reduction in dopamine activity, either from withdrawal of dopaminergic agents or from blockade of dopamine receptors.

Risk Factors

One of the clearest risk factors in the development of NMS is the course of drug therapy chosen to treat a condition. Use of high-potency neuroleptics, a rapid increase in the dosage of neuroleptics, and use of long-acting forms of neuroleptics are all known to increase the risk of developing NMS.

It has been purported that there is a genetic risk factor for NMS, since identical twins have both presented with NMS in one case, and a mother and two of her daughters have presented with NMS in another case.

Demographically, it appears that males, especially those under forty, are at greatest risk for developing NMS, although it is unclear if the increased incidence is a result of greater neuroleptic use in men under forty. It has also been suggested that postpartum women may be at a greater risk for NMS.

An important risk factor for this condition is Lewy body dementia. These patients are extremely sensitive to neuroleptics. As a result, neuroleptics should be used cautiously in all cases of dementia.

Pathophysiology

The mechanism is commonly thought to depend on decreased levels of dopamine activity due to:

  • Dopamine receptor blockade.
  • Genetically reduced function of dopamine receptor D2.

It has been proposed that blockade of D2-like (D2, D3 and D4) receptors induce massive glutamate release, generating catatonia, neurotoxicity and myotoxicity. Additionally, the blockade of diverse serotonin receptors by atypical antipsychotics and activation of 5HT1 receptors by certain of them reduces GABA release and indirectly induces glutamate release, worsening this syndrome.

The muscular symptoms are most likely caused by blockade of the dopamine receptor D2, leading to abnormal function of the basal ganglia similar to that seen in Parkinson’s disease.

However, the failure of D2 dopamine receptor antagonism, or dopamine receptor dysfunction, do not fully explain the presenting symptoms and signs of NMS, as well as the occurrence of NMS with atypical antipsychotic drugs with lower D2 dopamine activity. This has led to the hypothesis of sympathoadrenal hyperactivity (results from removing tonic inhibition from the sympathetic nervous system) as a mechanism for NMS. Release of calcium is increased from the sarcoplasmic reticulum with antipsychotic usage. This can result in increased muscle contractility, which can play a role in the breakdown of muscle, muscle rigidity, and hyperthermia. Some antipsychotic drugs, such as typical neuroleptics, are known to block dopamine receptors; other studies have shown that when drugs supplying dopamine are withdrawn, symptoms similar to NMS present themselves.

There is also thought to be considerable overlap between malignant catatonia and NMS in their pathophysiology, the former being idiopathic and the latter being the drug-induced form of the same syndrome.

The raised white blood cell count and creatine phosphokinase (CPK) plasma concentration seen in those with NMS is due to increased muscular activity and rhabdomyolysis (destruction of muscle tissue). The patient may suffer hypertensive crisis and metabolic acidosis. A non-generalized slowing on an EEG is reported in around 50% of cases.

The fever seen with NMS is believed to be caused by hypothalamic dopamine receptor blockade. The peripheral problems (the high white blood cell and CPK count) are caused by the antipsychotic drugs. They cause an increased calcium release from the sarcoplasmic reticulum of muscle cells which can result in rigidity and eventual cell breakdown. No major studies have reported an explanation for the abnormal EEG, but it is likely also attributable to dopamine blockage leading to changes in neuronal pathways.

Diagnosis

Differential Diagnosis

Differentiating NMS from other neurological disorders can be very difficult. It requires expert judgement to separate symptoms of NMS from other diseases. Some of the most commonly mistaken diseases are encephalitis, toxic encephalopathy, status epilepticus, heat stroke, catatonia and malignant hyperthermia. Due to the comparative rarity of NMS, it is often overlooked and immediate treatment for the syndrome is delayed. Drugs such as cocaine and amphetamine may also produce similar symptoms.

The differential diagnosis is similar to that of hyperthermia, and includes serotonin syndrome. Features which distinguish NMS from serotonin syndrome include bradykinesia, muscle rigidity, and a high white blood cell count.

Treatment

NMS is a medical emergency and can lead to death if untreated. The first step is to stop the antipsychotic medication and treat the hyperthermia aggressively, such as with cooling blankets or ice packs to the axillae and groin. Supportive care in an intensive care unit capable of circulatory and ventilatory support is crucial. The best pharmacological treatment is still unclear. Dantrolene has been used when needed to reduce muscle rigidity, and more recently dopamine pathway medications such as bromocriptine have shown benefit. Amantadine is another treatment option due to its dopaminergic and anticholinergic effects. Apomorphine may be used however its use is supported by little evidence. Benzodiazepines may be used to control agitation. Highly elevated blood myoglobin levels can result in kidney damage, therefore aggressive intravenous hydration with diuresis may be required. When recognised early NMS can be successfully managed; however, up to 10% of cases can be fatal.

Should the affected person subsequently require an antipsychotic, trialling a low dose of a low-potency atypical antipsychotic is recommended.

Prognosis

The prognosis is best when identified early and treated aggressively. In these cases NMS is not usually fatal. In earlier studies the mortality rates from NMS ranged from 20%-38%, but by 2009 mortality rates were reported to have fallen below 10% over the previous two decades due to early recognition and improved management. Re-introduction to the drug that originally caused NMS to develop may also trigger a recurrence, although in most cases it does not.

Memory impairment is a consistent feature of recovery from NMS, and is usually temporary though in some cases may become persistent.

Epidemiology

Pooled data suggest the incidence of NMS is between 0.2%-3.23%. However, greater physician awareness coupled with increased use of atypical anti-psychotics have likely reduced the prevalence of NMS. Additionally, young males are particularly susceptible and the male-female ratio has been reported to be as high as 2:1.

Research

While the pathophysiology of NMS remains unclear, the two most prevalent theories are:

  • Reduced dopamine activity due to receptor blockade.
  • Sympathoadrenal hyperactivity and autonomic dysfunction.

In the past, research and clinical studies seemed to corroborate the D2 receptor blockade theory in which antipsychotic drugs were thought to significantly reduce dopamine activity by blocking the D2 receptors associated with this neurotransmitter. However, recent studies indicate a genetic component to the condition. In support of the sympathoadrenal hyperactivity model proposed, it has been hypothesized that a defect in calcium regulatory proteins within the sympathetic neurons may bring about the onset of NMS. This model of NMS strengthens its suspected association with malignant hyperthermia in which NMS may be regarded as a neurogenic form of this condition which itself is linked to defective calcium-related proteins.

The introduction of atypical antipsychotic drugs, with lower affinity to the D2 dopamine receptors, was thought to have reduced the incidence of NMS. However, recent studies suggest that the decrease in mortality may be the result of increased physician awareness and earlier initiation of treatment rather than the action of the drugs themselves. NMS induced by atypical drugs also resembles “classical” NMS (induced by “typical” antipsychotic drugs), further casting doubt on the overall superiority of these drugs.

What is Tacrine?

Introduction

Tacrine is a centrally acting acetylcholinesterase inhibitor and indirect cholinergic agonist (parasympathomimetic).

It was the first centrally acting cholinesterase inhibitor approved for the treatment of Alzheimer’s disease, and was marketed under the trade name Cognex. Tacrine was first synthesised by Adrien Albert at the University of Sydney in 1949. It also acts as a histamine N-methyltransferase inhibitor.

Clinical Use

Tacrine was the prototypical cholinesterase inhibitor for the treatment of Alzheimer’s disease. William K. Summers received a patent for this use in 1989. Studies found that it may have a small beneficial effect on cognition and other clinical measures, though study data was limited and the clinical relevance of these findings was unclear.

Tacrine has been discontinued in the US in 2013, due to concerns over safety.

Tacrine was also described as an analeptic agent used to promote mental alertness.

Adverse Effects

  • Very common (>10% incidence) adverse effects include:
    • Increased LFTs.
    • Nausea.
    • Vomiting.
    • Diarrhoea.
    • Headache.
    • Dizziness.
  • Common (1-10% incidence) adverse effects include:
    • Indigestion.
    • Belching.
    • Abdominal pain.
    • Myalgia – muscle pain.
    • Confusion.
    • Ataxia – decreased control over bodily movements.
    • Insomnia.
    • Rhinitis.
    • Rash.
    • Fatigue.
    • Weight loss.
    • Constipation.
    • Somnolence.
    • Tremor.
    • Anxiety.
    • Urinary incontinence.
    • Hallucinations.
    • Agitation.
    • Conjunctivitis (a link to tacrine treatment has not been conclusively proven).
    • Diaphoresis – sweating.
  • Uncommon/rare (<1% incidence) adverse effects include:
    • Hepatotoxicity (that is toxic effects on the liver).
    • Ototoxicity (hearing/ear damage; a link to tacrine treatment has not been conclusively proven).
    • Seizures.
    • Agranulocytosis (a link between treatment and this adverse effect has not been proven) – a potentially fatal drop in white blood cells, the body’s immune/defensive cells.
    • Taste changes.
  • Unknown incidence adverse effects include:
    • Urinary tract infection.
    • Delirium.
    • Other optic effects such as glaucoma, cataracts, etc. (also not conclusively linked to tacrine treatment).
    • Depression.
    • Suicidal ideation and behaviour.
    • Hypotension.
    • Bradycardia.

Overdose

As stated above, overdosage of tacrine may give rise to severe side effects such as nausea, vomiting, salivation, sweating, bradycardia, hypotension, collapse, and convulsions. Atropine is a popular treatment for overdose.

Pharmacokinetics

Major form of metabolism is in the liver via hydroxylation of benzylic carbon by CYP1A2. This forms the major metabolite 1-hydroxy-tacrine (velnacrine) which is still active.

What is an Anxiolytic?

Introduction

An anxiolytic (also anti-panic or anti-anxiety agent) is a medication or other intervention that reduces anxiety.

This effect is in contrast to anxiogenic agents which increase anxiety. Anxiolytic medications are used for the treatment of anxiety disorder and its related psychological and physical symptoms.

Medications

Barbiturates

Barbiturates are powerful anxiolytics but the risk of abuse and addiction is high. Many experts consider these drugs obsolete for treating anxiety but valuable for the short-term treatment of severe insomnia, though only after benzodiazepines or non-benzodiazepines have failed.

Benzodiazepines

Benzodiazepines are prescribed to quell panic attacks. Benzodiazepines are also prescribed in tandem with an antidepressant for the latent period of efficacy associated with many ADs for anxiety disorder. There is risk of benzodiazepine withdrawal and rebound syndrome if BZDs are rapidly discontinued. Tolerance and dependence may occur. The risk of abuse in this class of medication is smaller than in that of barbiturates. Cognitive and behavioural adverse effects are possible.

Benzodiazepines include: Alprazolam (Xanax), Bromazepam, Chlordiazepoxide (Librium), Clonazepam (Klonopin), Diazepam (Valium), Lorazepam (Ativan), Oxazepam, Temazepam, and Triazolam.

Antidepressants

Antidepressant medications can reduce anxiety. The SSRIs paroxetine and lexapro and SNRIs venlafaxine and duloxetine are US Food and Drug Administration (FDA) approved to treat generalised anxiety disorder.

Selective Serotonin Reuptake Inhibitors

Selective serotonin reuptake inhibitors (SSRIs) are a class of medications used in the treatment of depression, anxiety disorders, OCD and some personality disorders. SSRIs can increase anxiety initially due to negative feedback through the serotonergic autoreceptors, for this reason a concurrent benzodiazepine can be used until the anxiolytic effect of the SSRI occurs.

Serotonin-Norepinephrine Reuptake Inhibitors

Serotonin-norepinephrine reuptake inhibitor (SNRIs) include venlafaxine and duloxetine drugs. Venlafaxine, in extended release form, and duloxetine, are indicated for the treatment of GAD. SNRIs are as effective as SSRIs in the treatment of anxiety disorders.

Tricyclic Antidepressants

Tricyclic antidepressants (TCAs) have anxiolytic effects; however, side effects are often more troubling or severe and overdose is dangerous. They’re effective, but they’ve generally been replaced by antidepressants that cause fewer adverse effects. Examples include imipramine, doxepin, amitriptyline, nortriptyline and desipramine.

Tetracyclic Antidepressant

Tetracyclic antidepressants, such as Mirtazapine, have demonstrated anxiolytic effect comparable to SSRIs while rarely causing or exacerbating anxiety. Mirtazapine’s anxiety reduction tends to occur significantly faster than SSRIs.

Monoamine Oxidase Inhibitors

Monoamine oxidase inhibitors (MAOIs) are first generation antidepressants effective for anxiety treatment but their dietary restrictions, adverse effect profile and availability of newer medications have limited their use. MAOIs include phenelzine, isocarboxazid and tranylcypromine. Pyrazidol is a reversible MAOI that lacks dietary restriction.

Sympatholytics

Sympatholytics are a group of anti-hypertensives which inhibit activity of the sympathetic nervous system. Beta blockers reduce anxiety by decreasing heart rate and preventing shaking. Beta blockers include propranolol, oxprenolol, and metoprolol. The Alpha-1 agonist prazosin could be effective for PTSD. The Alpha-2 agonists clonidine and guanfacine have demonstrated both anxiolytic and anxiogenic effects.

Miscellaneous

Buspirone

Buspirone (Buspar) is a 5-HT1A receptor agonist used to treated generalised anxiety disorder. If an individual has taken a benzodiazepine, buspirone will be less effective.

Pregabalin

Pregabalin (Lyrica) produces anxiolytic effect after one week of use comparable to lorazepam, alprazolam, and venlafaxine with more consistent psychic and somatic anxiety reduction. Unlike BZDs, it does not disrupt sleep architecture nor does it cause cognitive or psychomotor impairment.

Hydroxyzine

Hydroxyzine (Atarax) is an antihistamine originally approved for clinical use by the FDA in 1956. Hydroxyzine has a calming effect which helps ameliorate anxiety. Hydroxyzine efficacy is comparable to benzodiazepines in the treatment of generalised anxiety disorder. Hydroxyzine is typically only used for short term anxiety relief.

Phenibut

Phenibut (Anvifen, Fenibut, Noofen) is an anxiolytic used in Russia. Phenibut is a GABAB receptor agonist, as well as an antagonist at α2δ subunit-containing voltage-dependent calcium channels (VDCCs), similarly to gabapentinoids like gabapentin and pregabalin. The medication is not approved by the FDA for use in the United States, but is sold online as a supplement.

Mebicar

Mebicar is an anxiolytic produced in Latvia and used in Eastern Europe. Mebicar has an effect on the structure of limbic-reticular activity, particularly on the hypothalamus, as well as on all 4 basic neuromediator systems – γ aminobutyric acid (GABA), choline, serotonin and adrenergic activity. Mebicar decreases noradrenaline, increases serotonin, and exerts no effect on dopamine.

Fabomotizole

Fabomotizole (Afobazole) is an anxiolytic drug launched in Russia in the early 2000s. Its mechanism of action is poorly defined, with GABAergic, NGF and BDNF release promoting, MT1 receptor agonism, MT3 receptor antagonism, and sigma agonism thought to have some involvement.

Bromantane

Bromantane is a stimulant drug with anxiolytic properties developed in Russia during the late 1980s. Bromantane acts mainly by facilitating the biosynthesis of dopamine, through indirect genomic upregulation of relevant enzymes (tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AAAD).

Emoxypine

Emoxypine is an antioxidant that is also a purported anxiolytic. Its chemical structure resembles that of pyridoxine, a form of vitamin B6.

Menthyl Isovalerate

Menthyl isovalerate is a flavouring food additive marketed as a sedative and anxiolytic drug in Russia under the name Validol.

Racetams

Some racetam based drugs such as aniracetam can have an antianxiety effect.

Etifoxine

Having similar anxiolytic effects as benzodiazepine drugs, etifoxine does not produce the same levels of sedation and ataxia. Further, etifoxine does not affect memory and vigilance, and does not induce rebound anxiety, drug dependence, or withdrawal symptoms.

Alcohol

Ethanol is sometimes used as an anxiolytic by self-medication. fMRI can measure the anxiolytic effects of alcohol in the human brain.

Alternatives to Medication

Cognitive behavioural therapy (CBT) is an effective treatment for panic disorder, social anxiety disorder, generalized anxiety disorder, and obsessive-compulsive disorder, while exposure therapy is the recommended treatment for anxiety related phobias. Healthcare providers can guide those with anxiety disorder by referring them to self-help resources. Sometimes medication is combined with psychotherapy but research has not found a benefit of combined pharmacotherapy and psychotherapy versus monotherapy.

If CBT is found ineffective, both the Canadian and American medical associations then suggest the use of a potent, long lasting benzodiazepine such as clonazepam and an antidepressant, usually Prozac for its effectiveness.

What is a Serotonergic Drug?

Introduction

Serotonergic means “pertaining to or affecting serotonin”.

Background

Serotonin is a neurotransmitter. A synapse is serotonergic if it uses serotonin as its neurotransmitter. A serotonergic neuron produces serotonin. A substance is serotonergic if it produces its effects via interactions with the serotonin system, such as by stimulating or blocking neurotransmission.

A serotonergic or serotoninergic agent is any chemical that modifies the effects of serotonin in the body. Some different types of serotonergics drugs include the following:

  • Serotonin receptor agonists and antagonists;
  • Serotonin reuptake inhibitors; and
  • Serotonin releasing agents.