Antipsychotic

Olanzapine (Zyprexa), an example of a second-generation antipsychotic

Antipsychotics (also known as neuroleptics or major tranquilizers) are a class of psychiatric medication primarily used to manage psychosis (including delusions, hallucinations, or disordered thought), particularly in schizophrenia and bipolar disorder, and is increasingly being used in the management of non-psychotic disorders (ATC code N05A). The word neuroleptic originates from the Greek word lepsis ("seizure" or "fit").

A first generation of antipsychotics, known as typical antipsychotics, was discovered in the 1950s. Most of the drugs in the second generation, known as atypical antipsychotics, have been developed more recently, although the first atypical antipsychotic, clozapine, was discovered in the 1950s and introduced clinically in the 1970s. Both generations of medication tend to block receptors in the brain's dopamine pathways, but atypicals tend to act on serotonin receptors as well.

Notable and relatively common adverse effects of antipsychotics include extrapyramidal symptoms (which involve motor control) and hyperprolactinaemia primarily in typicals and weight gain and metabolic abnormalities mostly in atypicals. Temporary withdrawal symptoms including insomnia, agitation, psychosis, and motor disorders may occur during dosage reduction of antipsychotics, and can be mistaken for the return of the underlying condition.

Medical uses

Antipsychotics are most frequently used for the following conditions:

• Schizophrenia
• Schizoaffective disorder most commonly in conjunction with either an antidepressant (in the case of the depressive subtype) or a mood stabiliser (in the case of the bipolar subtype).
• Bipolar disorder (acute mania and mixed episodes may be treated with either typical or atypical antipsychotics, although atypical antipsychotics are usually preferred seeing how they tend to have more favourable adverse effect profiles and, according to a recent meta-analysis, they tend to have a lower liability for causing conversion from mania to depression. Bipolar depression can be treated with quetiapine, olanzapine or lurasidone. As for bipolar maintenance several atypical antipsychotics have demonstrated efficacy in preventing manic/mixed relapse but few (with the exception of quetiapine and olanzapine) have demonstrated efficacy in preventing manic, mixed and depressive relapse as a monotherapy)
• Psychotic depression. In this indication it is a common practice for the attending psychiatrist to prescribe a combination of an atypical antipsychotic and an antidepressant as this practice is best supported by the evidence.
• Treatment-resistant (and not necessarily psychotic) major depression as an adjunct to standard antidepressant therapy.

They are not recommended for dementia or insomnia unless other treatments have not worked. They are not recommended in children unless other treatments are not effective or unless the child has psychosis. Two different antipsychotics should not typically be used in the same person.

Schizophrenia

In people with schizophrenia less than half (41%) showed any therapeutic response to an atypical antipsychotic, compared to 24% on placebo, there is a decline in treatment response over time, and potentially a biases in the literature in favor of these medication. Risperidone (an atypical antipsychotic), shows only slight benefit compared with placebo and that, despite its widespread use, evidence remains limited, poorly reported and probably biased in favor of risperidone due to pharmaceutical company funding of trials.

Some doubts have been raised about the long-term effectiveness of antipsychotics for schizophrenia, in part because two World Health Organization studies found individuals diagnosed with schizophrenia tend to have better long-term outcomes in developing countries (where there is lower availability and use of antipsychotics and mental health problems are treated with more informal, community-led methods only) than in developed countries.

Some argue that the evidence for antipsychotics from discontinuation-relapse studies may be flawed, because they do not take into account that antipsychotics may sensitize the brain and provoke psychosis if discontinued, which may then be wrongly interpreted as a relapse of the original condition. Evidence from comparison studies indicates that at least some individuals with schizophrenia recover from psychosis without taking antipsychotics, and may do better in the long term than those that do take antipsychotics. Some argue that, overall, the evidence suggests that antipsychotics only help if they are used selectively and are gradually withdrawn as soon as possible and have referred to the "Myth of the antipsychotic".

The methods used in trials of antipsychotics, despite stating that the overall quality is "rather good," reported issues with the selection of participants (including that in schizophrenia trials up to 90% of people who are generally suitable do not meet the elaborate inclusion and exclusion criteria, and that negative symptoms have not been properly assessed despite companies marketing the newer antipsychotics for these); issues with the design of trials (including pharmaceutical company funding of most of them, and inadequate experimental "blinding" so that trial participants could sometimes tell whether they were on placebo or not); and issues with the assessment of outcomes (including the use of a minimal reduction in scores to show "response," lack of assessment of quality of life or recovery, a high rate of discontinuation, selective highlighting of favorable results in the abstracts of publications, and poor reporting of side-effects).

While flupenthixol an injectable form of antipsychotic which is given every few weeks is extensively used there is little evidence to support this use. There is little long term data on the benefits of antipsychotics (beyond two to three years). It is recommended that if a person is without symptoms for a year stopping the use of antipsychotics be considered.

Bipolar disorder

Antipsychotics are routinely used, often in conjunction with mood stabilisers such as lithium/valproate, as a first-line treatment for manic and mixed episodes associated with bipolar disorder. The reason for this combination is the therapeutic delay of the aforementioned mood stabilisers (for valproate therapeutic effects are usually seen around five days after treatment is commenced whereas lithium usually takes at least a week before the full therapeutic effects are seen) and the comparatively rapid antimanic effects of antipsychotic drugs. The antipsychotics have a documented efficacy when used alone in acute mania/mixed episodes.

Three atypical antipsychotics (lurasidone, olanzapine and quetiapine) have also been found to possess efficacy in the treatment of bipolar depression as a monotherapy. Whereas only olanzapine and quetiapine have been proven to be effective broad-spectrum (i.e. against all three types of relapse— manic, mixed and depressive) prophylactic (or maintenance) treatments in patients with bipolar disorder. A recent Cochrane review also found that olanzapine had a less favourable risk/benefit ratio than lithium as a maintenance treatment for bipolar disorder.

The American Psychiatric Association and the UK National Institute for Health and Clinical Excellence recommend antipsychotics for managing acute psychotic episodes in schizophrenia or bipolar disorder, and as a longer-term maintenance treatment for reducing the likelihood of further episodes. They state that response to any given antipsychotic can be variable so that trials may be necessary, and that lower doses are to be preferred where possible. A number of studies have looked at levels of "compliance" or "adherence" with antipsychotic regimes and found that discontinuation (stopping taking them) by patients is associated with higher rates of relapse, including hospitalization.

Dementia

Antipsychotics in old age dementia showed a modest benefit compared to placebo in managing aggression or psychosis, but this is combined with a significant increase in serious adverse events. Thus antipsychotics should not be used routinely to treat dementia with aggression or psychosis, but may be an option in a few cases where there is severe distress or risk of physical harm to others. Psychosocial interventions may reduce the need for antipsychotics.

Unipolar Depression

A number of second-generation (or atypical) antipsychotics have proven to be effective adjuncts in the treatment of major depressive disorder of which aripiprazole, quetiapine and olanzapine (when used in conjunction with fluoxetine) have received FDA labelling for this indication. Quetiapine has also proven effective as a monotherapy in major depressive disorder.

Other

Besides the above uses antipsychotics may be used for Obsessive-compulsive disorder, Posttraumatic stress disorder, personality disorders, Tourette syndrome, autism (for which both aripiprazole and risperidone are FDA-labelled) and agitation in those with dementia. Evidence however does not support the use of atypical antipsychotics in eating disorders or personality disorder. Risperidone may be useful for obsessive compulsive disorder. The use of low doses of antipsychotics for insomnia, while common, is not recommended as there is little evidence of benefit and concerns regarding adverse effects. Low dose antipsychotics may also be used in treatment of impulse-behavioural and cognitive-perceptual symptoms of borderline personality disorder.

In children they may be used in those with disruptive behavior disorders, mood disorders and pervasive developmental disorders or intellectual disability. Antipsychotics are only weakly recommended for Tourette syndrome as well they are effective side effects are common. The situation is similar in autism spectrum disorder. Much of the evidence for the off-label use of antipsychotics (for example, for dementia, OCD, PTSD, Personality Disorders, Tourette's) was of insufficient scientific quality to support such use, especially as there was strong evidence of increased risks of stroke, tremors, significant weight gain, sedation, and gastrointestinal problems. A UK review of unlicensed usage in children and adolescents reported a similar mixture of findings and concerns. A survey of children with pervasive developmental disorder found that 16.5% were taking an antipsychotic drug, most commonly for irritability, aggression, and agitation. Recently, risperidone was approved by the US FDA for the treatment of irritability in children and adolescents with autism.

Aggressive challenging behavior in adults with intellectual disability is often treated with antipsychotic drugs despite lack of an evidence base. A recent randomized controlled trial, however, found no benefit over placebo and recommended that the use of antipsychotics in this way should no longer be regarded as an acceptable routine treatment.

Typicals versus atypicals

While the atypical (second-generation) antipsychotics were marketed as offering greater efficacy and reduced side effects than typical medications this may not be true. One review concluded there were no differences while another found that atypicals were "only moderately more efficacious". These conclusions were, however, questioned by another review, which found that clozapine, amisulpride, and olanzapine and risperidone were more effective Clozapine has appeared to be more effective than other atypical antipsychotics, although it has previously been banned due to its potentially lethal side effects. While controlled clinical trials of atypicals reported that extrapyramidal symptoms occurred in 5–15% of patients, a study of bipolar disorder in a real world clinical setting found a rate of 63%, questioning the generalizability of the trials. Due to bias in the research the accuracy of comparisons of atypical antipsychotics is a concern.

In 2005 the US government body National Institute of 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 typical antipsychotic, perphenazine, among 1493 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 44 pounds (20 kg) over 18 months) and increases in glucose, cholesterol, and triglycerides. The mean and maximal doses used for olanzapine were considerably higher than standard practice, and this has been postulated as a biasing factor that may explain olanzapine's superior efficacy over the other atypical antipsychotics studied, where doses were more in line with clinically relevant practices. 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, although more patients discontinued perphenazine owing to extrapyramidal effects compared to the atypical agents (8% vs. 2% to 4%).

Compliance has not been shown to be different between the two types.

Many researchers question the first-line prescribing of atypicals over typicals, and some even question the distinction between the two classes. In contrast, other researchers point to the significantly higher risk of tardive dyskinesia and EPS with the typicals and for this reason alone recommend first-line treatment with the atypicals, notwithstanding a greater propensity for metabolic adverse effects in the latter. The UK government organization NICE recently revised its recommendation favoring atypicals, to advise that the choice should be an individual one based on the particular profiles of the individual drug and on the patient's preferences.

The re-evaluation of the evidence has not necessarily slowed the bias towards prescribing the atypicals.

Adverse effects

Antipsychotics are associated with a range of side effects. It is well-recognized that many people stop taking them (around two-thirds even in controlled drug trials) due in part to adverse effects.

Common (≥1% and up to 50% incidence for most antipsychotic drugs) adverse effects of antipsychotics include

• Sedation (particularly common in patients on clozapine, olanzapine, quetiapine, chlorpromazine and zotepine)
• Headaches
• Dizziness
• Diarrhoea
• Anxiety
• Extrapyramidal side effects (particularly common in patients on first-generation antipsychotics) which includes:

- Akathisia — an often distressing sense of inner restlessness.

- Dystonia

- Parkinsonism

- Tremor

• Hyperprolactinaemia (rare for those on clozapine, quetiapine and aripiprazole) which can cause:

- Galactorrhoea — unusual secretion of breast milk.

- Gynaecomastia

- Sexual dysfunction (in both sexes)

- Osteoporosis

• Orthostatic hypotension
• Weight gain (particularly prominent in patients on clozapine, olanzapine, quetiapine and zotepine)
• Anticholinergic side effects such as:

- Amnesia (although this is not a common adverse effect in patients on antipsychotics)

- Angle-closure glaucoma (also rare in patients on antipsychotics)

- Blurred vision

- Constipation

- Dry mouth (although hypersalivation may also occur)

- Reduced perspiration

• Tardive dyskinesia appears to be more frequent in those on high-potency first-generation antipsychotics such as haloperidol and tends to appear after chronic and not acute treatment. It is characterised by slow (hence the tardive) repetitive, involuntary and purposeless movements, most often of the face, lips, legs or torso which tend to resist treatment and are frequently irreversible. The rate of appearance of TD is about 5% per year of use of antipsychotic drug (whatever the drug used).

Rare/Uncommon (<1% incidence for most antipsychotic drugs) adverse effects of antipsychotics include

• Blood dyscarias (e.g. agranulocytosis, leukopaenia and neutropaenia) which is more common in patients on clozapine.
• Metabolic syndrome and other metabolic problems such as Type II diabetes mellitus — particularly common with clozapine, olanzapine and zotepine. In American studies African Americans appeared to be at a heightened risk for developing type II diabetes mellitus. Evidence suggests that females are more sensitive to the metabolic side effects of first-generation antipsychotic drugs than males. Metabolic adverse effects appears to be mediated by the following mechanisms:

- Blocking the M₃ muscarinic acetylcholine receptor which is responsible for regulating the release of insulin.

- Inappropriately changing the body's energy source from carbohydrates to lipids.

- Causing weight gain by antagonising the histamine H₁ and serotonin 5-HT_2Creceptors and perhaps by interacting with other neurochemical pathways in the central nervous system.

• Neuroleptic malignant syndrome a potentially fatal condition characterised by:

- Autonomic instability which can manifest itself with tachycardia, nausea, vomiting, diaphoresis, etc.

- Hyperthermia — elevated body temperature.

- Mental status change (confusion, hallucinations, coma, etc.)

- Muscle rigidity

- Laboratory abnormalities (e.g. elevated creatinine kinase, reduced iron plasma levels, electrolyte abnormalities, etc.)

• Pancreatitis
• Pharyngitis
• QT interval prolongation — more prominent in patients on amisulpride, pimozide, sertindole, thioridazine and ziprasidone.
• Seizures which is particularly common in patients on chlorpromazine and clozapine.
• Thromboembolism
• Myocardial infarction
• Stroke
• Torsades de Pointes

Some studies have found decreased life expectancy associated with the use of antipsychotics, and argued that more studies are needed. Antipsychotics may also increase the risk of early death in individuals with dementia. In individuals without psychosis, doses of antipsychotics can produce the "negative symptoms" of schizophrenia such as amotivation. Antipsychotics typically worsen symptoms in people who suffer from depersonalisation disorder. Antipsychotic polypharmacy (prescribing two or more antipsychotics at the same time for an individual) is said to be a common practice but not necessarily evidence-based or recommended, and there have been initiatives to curtail it. Similarly, the use of excessively high doses (often the result of polypharmacy) continues despite clinical guidelines and evidence indicating that it is usually no more effective but is usually more harmful.

Other

Chronic treatment with antipsychotics may reduce amounts of brain tissue and potentially cause some of the symptoms believed to be due to schizophrenia According to studies in macaque monkeys cell loss only affects the number of glial cells and not the numbers of neuronal cells. Continuous use of neuroleptics has been shown to decrease the total brain volume by 10% in macaque monkeys. The effects may differ for typical versus atypical antipsychotics and may interact with different stages of disorders. Such effects were not clearly tested for by pharmaceutical companies prior to obtaining approval for placing the drugs on the market.

A minor loss of brain tissue has been reported in schizophrenics treated with antipsychotics. Brain volume was negatively correlated with both duration of illness and antipsychotic dosage. No association was found with severity of illness or abuse of other substances. An accompanying editorial said: "The findings should not be construed as an indication for discontinuing the use of antipsychotic medications as a treatment for schizophrenia. But they do highlight the need to closely monitor the benefits and adverse effects of these medications in individual patients, to prescribe the minimal amount needed to achieve the therapeutic goal [and] to consider the addition of nonpharmacological approaches that may improve outcomes."

Withdrawal

Withdrawal symptoms from antipsychotics may emerge during dosage reduction and discontinuation. Withdrawal symptoms can include nausea, emesis, anorexia, diarrhea, rhinorrhea, diaphoresis, myalgia, paresthesia, anxiety, agitation, restlessness, and insomnia. The psychological withdrawal symptoms can include psychosis, and can be mistaken for a relapse of the underlying disorder. Conversely, the withdrawal syndrome may also be a trigger for relapse. Better management of the withdrawal syndrome may improve the ability of individuals to discontinue antipsychotics.

Tardive dyskinesia may abate during withdrawal from the antispsychotic agent, or it may persist. Withdrawal-related psychosis from antipsychotics is called "supersensitivity psychosis", and is attributed to increased number and sensitivity of brain dopamine receptors, due to blockade of dopaminergic receptors by the antipsychotics, which often leads to exacerbated symptoms in the absence of neuroleptic medication. Efficacy of antipsychotics may likewise be reduced over time, due to this development of drug tolerance.

Withdrawal effects may also occur when switching a person from one antipsychotic to another, (presumably due to variations of potency and receptor activity). Such withdrawal effects can include cholinergic rebound, an activation syndrome, and motor syndromes including dyskinesias. These adverse effects are more likely during rapid changes between antipsychotic agents, so making a gradual change between antipsychotics minimises these withdrawal effects. The British National Formulary recommends a gradual withdrawal when discontinuing antipsychotic treatment to avoid acute withdrawal syndrome or rapid relapse. The process of cross-titration involves gradually increasing the dose of the new medication while gradually decreasing the dose of the old medication.

List of agents

Chlorpromazine.

Haloperidol.

Quetiapine.

Clinically used antipsychotic medications are listed below by drug group. Trade names appear in parentheses.

Notes:

† indicates drugs that are no longer marketed in English-speaking countries.

‡ denotes drugs that are no longer (or were never to begin with) marketed in the US. Some antipsychotics are not firmly placed in either first-generation or second-generation classes.

# denotes drugs that have been withdrawn worldwide.

First-generation

Main article: Typical antipsychotic

Butyrophenones

Main article: Butyrophenones

• Benperidol (Anguil, Benguil, Frenactil, Glianimon)^‡
• Bromperidol (Bromodol, Impromen)^†
• Droperidol (Droleptan, Inapsine)^‡
• Haloperidol (Haldol, Serenace)
• Moperone (Luvatren (discontinued))^†
• Pipamperone (Dipiperon, Piperonil (discontinued))^†
• Timiperone (Celmanil, Tolopelon)^†

Diphenylbutylpiperidine

• Fluspirilene (Imap)
• Penfluridol (Semap)
• Pimozide (Orap)

Phenothiazines

Main article: Phenothiazines

• Acepromazine (Plegicil)^† — although it is mostly used in veterinary medicine.
• Chlorpromazine (Largactil, Thorazine (discontinued))
• Cyamemazine (Tercian)^†
• Dixyrazine (Esucos)^†
• Fluphenazine (Modecate, Permitil (discontinued), Prolixin (discontinued)) – Available in decanoate (long-acting) form
• Levomepromazine (Levinan, Levoprome (discontinued), Nozinan)^‡
• Mesoridazine (Lidanil, Serentil (discontinued))^†
• Perazine (Peragal, Perazin, Pernazinum, Taxilan)
• Pericyazine (Neulactil, Neuleptil)^‡
• Perphenazine (Trilafon)
• Pipotiazine (Lonseren, Piportil)^‡
• Prochlorperazine (Compazine)
• Promazine (Prozine, Sparine (discontinued))
• Promethazine (Avomine, Phenergan)
• Prothipendyl (Dominal)^†
• Thioproperazine (Majeptil)^‡ (only English-speaking country it is available in is Canada)
• Thioridazine (Aldazine (discontinued), Mellaril (discontinued), Melleril (discontinued))
• Trifluoperazine (Stelazine)
• Triflupromazine (Vesprin (discontinued))^†

Thioxanthenes

Main article: Thioxanthenes

• Chlorprothixene (Cloxan, Taractan, Truxal)^†
• Clopenthixol (Sordinol)
• Flupentixol (Depixol, Fluanxol)^‡
• Tiotixene (Navane, Thixit)
• Zuclopenthixol (Acuphase, Cisordinol, Clopixol)^‡

Others

• Clotiapine (Entumine, Etomine, Etumine)^‡
• Loxapine (Adasuve, Loxitane)
• Prothipendyl (Dominal)^†

Disputed/Unknown

This category is for drugs which have been called both first and second-generation, depending on the literature being used.

• Carpipramine (Defekton, Prazinil)^†
• Clocapramine (Clofekton, Padrasen)^†
• Molindone (Moban)^#
• Mosapramine (Cremin)^†
• Sulpiride (Meresa)^‡
• Sultopride (Barnetil, Topral)^†
• Veralipride (Agreal)^†

Second-generation

Main article: Atypical antipsychotic

• Amisulpride (Solian)^‡– Selective dopamine antagonist. Higher doses (greater than 400 mg) act upon post-synaptic dopamine receptors resulting in a reduction in the positive symptoms of schizophrenia, such as psychosis. Lower doses, however, act upon dopamine autoreceptors, resulting in increased dopamine transmission, improving the negative symptoms of schizophrenia. Lower doses of amisulpride have also been shown to have antidepressant and anxiolytic effects in non-schizophrenic patients, leading to its use in dysthymia and social phobias.
• Amoxapine (Asendin), active metabolite of loxapine, that's most frequently used as a tricyclic antidepressant and has, in a few clinical trials, been found to possess atypical antipsychotic effects.
• Aripiprazole (Abilify) – Partial agonist at the D₂ receptor unlike all other clinically-utilised antipsychotics.
• Asenapine (Saphris, Sycrest) is a 5-HT2A- and D2-receptor antagonist developed for the treatment of schizophrenia and acute mania associated with bipolar disorder.
• Clozapine (Clozaril) – Requires complete blood counts every one to four weeks due to the risk of agranulocytosis. It has unparalleled efficacy in the treatment of treatment-resistant schizophrenia.
• Blonanserin (Lonasen)^† — an antipsychotic that is used in Japan and Korea. May have a beneficial effect on cognition via its antagonism of the 5-HT₆ receptor.
• Iloperidone (Fanapt, Fanapta, and previously known as Zomaril) – Approved by the FDA in 2009, it is fairly well tolerated, although hypotension, dizziness, and somnolence were very common side effects. Has not received regulatory approval in other countries, however.
• Lurasidone (Latuda), recently approved by the FDA for schizophrenia and bipolar depression. Given once daily, it has shown mixed Phase III efficacy results but has a relatively well-tolerated side effect profile. It is also licensed for use as schizophrenia treatment in Canada. Not yet licensed elsewhere, however. Has procognitive effects via its antagonism of the 5-HT₇ receptor.
• Melperone (Buronil, Buronon, Eunerpan, Melpax, Neuril)^†, an atypical antipsychotic that is only used in a few European countries. No English-speaking country has licensed it to date.
• Nemonapride (Emilace)^†
• Olanzapine (Zyprexa) – Used to treat psychotic disorders including schizophrenia, acute manic episodes, and maintenance of bipolar disorder. Used as an adjunct to antidepressant therapy, especially to fluoxetine treatment in the form of Symbyax.
• Paliperidone (Invega)– Primary Metabolite of risperidone that was approved in 2006, it offers a controlled releaseonce-daily dose, or a once-monthly depot injection.
• Perospirone (Lullan)^† — has a higher incidence of extrapyramidal side effects than other atypical antipsychotics.
• Quetiapine (Seroquel) – Used primarily to treat bipolar disorder and schizophrenia. Also used and licensed in a few countries (including Australia, UK and US) as an adjunct to antidepressant therapy in patients with major depressive disorder. It's the only antipsychotic that's demonstrated efficacy as a monotherapy for the treatment of major depressive disorder. It indirectly serves as a norepinephrine reuptake inhibitor by means of its active metabolite, norquetiapine.
• Remoxipride (Roxiam)^# has a risk of causing aplastic anaemia and hence has been withdrawn from the market worldwide. It has also been found to possess relatively low (virtually absent) potential to induce hyperprolactinaemia and extrapyramidal symptoms, likely attributable to its comparatively weak binding to (and hence rapid dissociation from) the D₂ receptor.
• Risperidone (Risperdal) – Divided dosing is recommended until initial titration is completed, at which time the drug can be administered once daily. Used off-label to treat Tourette syndrome and anxiety disorder.
• Sertindole (Serdolect, Serlect)^‡. Sertindole was developed by the Danish pharmaceutical company H. Lundbeck. Like the other atypical antipsychotics, it is believed to have antagonist activity at dopamine and serotonin receptors in the brain.
• Trimipramine (Surmontil)
• Ziprasidone (Geodon, Zeldox) – Approved in 2004 to treat bipolar disorder. Side-effects include a prolonged QT interval in the heart, which can be dangerous for patients with heart disease or those taking other drugs that prolong the QT interval.
• Zotepine (Lodopin, Losizopilon, Nipolept, Setous) – An atypical antipsychotic indicated for acute and chronic schizophrenia. It is still used in Japan and was once used in Germany but it was recently discontinued.^†

Investigational agents

• Alstonine, an indole alkaloid found in a number of different plants and which serves as a 5-HT_2C receptor agonist. Attenuates MK-801-induced hyperlocomotion, social withdrawal and working memory deficits.
• Bifeprunox^‡‡

• Bitopertin a GlyT₁ inhibitor. Being investigated as a treatment for mostly negative and cognitive symptoms.
• Brexpiprazole a D₂/5-HT_1A partial agonist.
• Cannabidiol (CBD), one of the active constituents of cannabis that has antipsychotic effects, unlike the chief active constituent of cannabis, namely, tetrahydrocannabinol which has psychotomimetic effects.

• Cariprazine a D3-selective D2/D3 partial agonist.
• Pimavanserin a 5-HT_2A inverse agonist. Being investigated as an adjunct to antipsychotics in schizophrenia and as a monotherapy for Parkinson's disease psychosis.
• Pomaglumetad methionil^‡‡ a mGluR_2/3-selective agonist; development has been ceased due to negative phase III trial results both as a monotherapy and as an adjunct to antipsychotics.

• Vabicaserin^‡‡ a 5-HT_2C full agonist.
• Xanomeline^‡‡ a M₁ & M₄ agonist.

• Zicronapine

* where ^‡‡ indicates drugs for which development has ceased

Mechanism of action

All antipsychotic drugs tend to block D₂ receptors in the dopamine pathways of the brain. This means that dopamine released in these pathways has less effect. Excess release of dopamine in the mesolimbic pathway has been linked to psychotic experiences. It has also been proven less dopamine released in the prefrontal cortex in the brain, and excess dopamine released from all other pathways, has also been linked to psychotic experiences, caused by abnormal dopaminergic function as a result of patients suffering from schizophrenia or bipolar disorder. Various neuroleptics such as haloperidol and chlorpromazine suppress dopamine chemicals throughout its pathways, in order for dopamine receptors to function normally.

In addition of the antagonistic effects of dopamine, antipsychotics (particularly atypical neuroleptics) also partially antagonize 5-HT_2A receptors. Different alleles of the 5-HT_2A receptor have been associated with schizophrenia and other psychoses, including depression. Higher concentrations of 5-HT_2A receptors receptors in cortical and subcortical areas, particularly in the right caudate nucleus have been historically recorded. This is the same receptor that psychedelic drugs partially agonize to various degrees, some of which are associated with lower risk for mental disorder. SSRIs also indirectly agonize this receptor, by inducing higher levels of serotonin.

Typical antipsychotics are not particularly selective and also block dopamine receptors in the mesocortical pathway, tuberoinfundibular pathway, and the nigrostriatal pathway. Blocking D₂ receptors in these other pathways is thought to produce some of the unwanted side effects that the typical antipsychotics can produce (see above). They were commonly classified on a spectrum of low potency to high potency, where potency referred to the ability of the drug to bind to dopamine receptors, and not to the effectiveness of the drug. High-potency antipsychotics such as haloperidol, in general, have doses of a few milligrams and cause less sleepiness and calming effects than low-potency antipsychotics such as chlorpromazine and thioridazine, which have dosages of several hundred milligrams. The latter have a greater degree of anticholinergic and antihistaminergic activity, which can counteract dopamine-related side effects.

Atypical antipsychotic drugs have a similar blocking effect on D₂ receptors, however, most also act on serotonin receptors, especially 5-HT_2A and 5-HT_2C receptors. Both clozapine and quetiapine appear to bind just long enough to elicit antipsychotic effects but not long enough to induce extrapyramidal side effects and prolactin hypersecretion. 5-HT_2A antagonism increases dopaminergic activity in the nigrostriatal pathway, leading to a lowered extrapyramidal side effect liability among the atypical antipsychotics.

Comparison of medications

Tolerability

Tolerability

Generic name Discontinuation rate (OR with 95% CI in brackets) Anticholinergic effects Sedation EPSE Weight Gain Metabolic AEs QTc prolongation (ORs & 95% CIs) PE Hypotension Notes (e.g. notable AEs*) Amisulpride 0.43 (0.32-0.57) - - + + +/- +++ (0.66 [0.39-0.91]) +++/++ - Torsades de Pointes common on overdose. Has a comparatively low penetrability of the blood-brain barrier. Amoxapine ? ++ ++ +/- ++/+ ++/+ ++/+ ++/+ ++/+ Amoxapine is also an antidepressant. Very toxic in overdose due to the potential for renal failure and seizures. Aripiprazole 0.61 (0.51-0.72) - + +/- (Akathisia mostly) + +/- - (0.01 [–0.13-0·15]) - (can reduce prolactin levels) - Only clinically-utilised antipsychotic that does not act by antagonising the D2 receptor and rather partially agonises this receptor. Asenapine 0.69 (0.54-0.86) - ++ + + +/- ++/+ (0.30 [–0.04-0.65]) + + Oral hypoesthesia. Has a complex pharmacologic profile. Blonanserin ~0.7 + + ++/+ +/- +/- - ++/+ +/- Only used in a few East Asian countries. Chlorpromazine 0.65 (0.5-0.84) +++ +++ ++ ++ ++ ++ +++ +++ First marketed antipsychotic, sort of the prototypical low-potency first-generation (typical) antipsychotic. Clozapine 0.46 (0.32-0.65) +++ +++ - +++ +++ + - +++ Notable AEs: Agranulocytosis, neutropaenia, leukopaenia and myocarditis. Dose-dependent seizure risk. Overall the most effective antipsychotic, on average. Usually reserved for treatment-resistant cases or highly suicidal patients. Droperidol ? +/- +/- +++ +/- +/- ? +++ ? Mostly used for postoperative nausea and vomiting. Flupenthixol ? ++ + ++ ++ ++ + +++ + Also used in lower doses for depression. Fluphenazine 0.69 (0.24-1.97) ++ + +++ + + + +++ + High-potency first-generation (typical) antipsychotic. Haloperidol 0.8 (0.71-0.90) + + +++ + +/- + (0.11 [0.03-0.19]) +++ + Prototypical high-potency first-generation (typical) antipsychotic. Iloperidone 0.69 (0.56-0.84) - +/- + ++ ++ ++ (0.34 [0.22-0.46]) ++/+ + ? Levomepromazine ? +++ +++ ++/+ ++ ++ ? +++ +++ Also used as an analgesic, agitation, anxiety and emesis. Loxapine 0.52 (0.28-0.98) + ++ +++ + +/- ? +++ ++ ? Lurasidone 0.77 (0.61-0.96) - - ++/+ - - - (–0.10 [–0.21-0.01]) ++/+ - May be particularly helpful in ameloriating the cognitive symptoms of schizophrenia, likely due to its 5-HT7 receptor. Melperone ? - +/- - +/- +/- ++ - ++/+ Several smaller low-quality clinical studies have reported its efficacy in the treatment of treatment-resistant schizophrenia. Only approved for use in a few European countries. It is known that off-licence prescribing of melperone is occurring in the United Kingdom. Is a butyrophenone, low-potency atypical antipsychotic that has been tried as a treatment for Parkinson's disease psychosis, although with negative results. Molindone ? - ++/+ + - - ? +++ +/- Withdrawn from the market. Seems to promote weight loss (which is rather unique for an antipsychotic seeing how they tend to promote weight gain). Olanzapine 0.46 (0.41-0.52) + ++ + +++ +++ + (0.22 [0.11-0.31]) + + ? Paliperidone 0.48 (0.39-0.58) - - ++/+ (dose-dependent) ++ + - (0.05 [–0.18-0.26]) +++ ++ Active metabolite of risperidone. Perazine 0.62 (0.35-1.10) ? ? ? ? ? ? ? ? Limited data available on adverse effects. Pericyazine ? +++ +++ + ++ + ? +++ ++ Also used to treat severe anxiety. Not licensed for use in the US. Perospirone ? +/- + ++/+ +/- ? - ++/+ - Usually grouped with the atypical antipsychotics despite its relatively high propensity for causing extrapyramidal side effects. Perphenazine 0.40 (0.08-1.90) + + +++ + + + +++ + Has additional antiemetic effects. Pimozide 0.66 (0.45-0.98) + + + + + +++ +++ + High potency first-generation (typical) antipsychotic. Pipotiazine ? ++ ++ ++ ++ + ? +++ ++ Only available in the UK. Prochlorperazine ? ? ? +++ ? ? + +++ ? Primarily used in medicine as an antiemetic. Quetiapine 0.61 (0.52-0.71) ++/+ ++ - ++ ++/+ + (0.17 [0.06-0.29]) - ++ Binds to the D2 receptor in a hit and run fashion. That is it rapidly dissociates from said receptor and hence produces antipsychotic effects but does not bind to the receptor long enough to produce extrapyramidal side effects and hyperprolactinaemia. Remoxipride ? - +/- - +/- +/- - - - Removed from the market amidst concerns about an alarmingly high rate of aplastic anaemia. Risperidone 0.53 (0.46-0.60) - ++/+ (dose-dependent) ++ ++ ++/+ ++ (0.25 [0.15-0.36]) +++ ++ ? Sertindole 0.78 (0.61-0.98) - - - ++ ++/+ +++ (0.90 [0.76-1.02]) - +++ Not licensed for use in the US. Sulpiride 1.00 (0.25-4.00) - - + + +/- + +++/++ - Not licensed for use in the US. Thioridazine 0.67 (0.32-1.40) +++ +++ + ++ ++ +++ +++ +++ Dose-dependent risk for degenerative retinopathies. Found utility in reducing the resistance of multidrug and even extensively resistant strains of tuberculosis to antibiotics. Tiotixene ? - + +++ ++ ++/+ + +++ + ? Trifluoperazine 0.94 (0.59-1.48) +/- + +++ + +/- ? +++ + ? Ziprasidone 0.72 (0.59 to 0.86) - ++ + - - ++ (0.41 [0.31 to 0.51]) ++/+ + ? Zotepine 0.69 (0.41 to 1.07) + +++ ++ +++/++ +++/++ ++ +++ ++ Dose-dependent risk of seizures. Not licensed for use in the US. Zuclopenthixol ? ++ ++ +++ ++ ++ ? +++ + Not licensed for use in the US. Note: "Notable" is to mean side effects that are particularly unique to the antipsychotic drug in question. e.g. clozapine is notorious for its ability to cause agranulocytosis. If data on the propensity of a particular drug to cause a particular AE is unavailable an estimation is substituted based on the pharmacologic profile of the drug. Acronyms used: AE - Adverse effect OR - Odds ratio CI - Confidence Interval EPSE - Extrapyramidal Side Effect QTc - Corrected QT interval PE - Prolactin elevation ' Legend: - very low propensity for this AE + low propensity/severity for this AE ++ moderate propensity/severity for this AE +++ high propensity/severity for this AE

Efficacy

Efficacy

Generic drug name Schizophrenia Mania Bipolar depression Bipolar maintenance Adjunct in major depression Amisulpride +++ ? ? ? ? (+++ in dysthymia) Aripiprazole ++ ++ - ++ (prevents manic and mixed but not depressive episodes) +++ Asenapine ++/+ ++ ? ++ ? Chlorpromazine ++ ? ? ? ? Clozapine +++ ? ? ? ? Haloperidol ++ +++ ? ? ? Iloperidone + ? ? ? ? Loxapine +++/++ +++ (only in the treatment of agitation) ? ? ? Lurasidone + ? +++ ? ? Melperone +++ ? ? ? ? Olanzapine +++ +++/++ ++ ++ (most effective at preventing manic/mixed relapse) ++ Paliperidone ++ +++/++ ? ? ? Perospirone + ? ? ? ? Quetiapine ++ ++ +++ +++ ++ Risperidone +++ +++ - ++ +++ Sertindole ++ ? ? ? ? Ziprasidone ++/+ + ? + ? Zotepine ++ ? ? ? ?

Binding affinity

Binding affinity

Ki [nM] toward cloned human receptors (unless otherwise specified) Generic drug name SERT 5-HT1A 5-HT2A 5-HT2C 5-HT6 5-HT7 α1A α2A α2C NET D1 D2 D3 D4 5-HT2A/D2 H1 M1 M3 Amisulpride >10,000 >10,000 8,304 >10,000 4,154 73.5 >10,000 1,114 1,540 >10,000 >10,000 2.2 2.4 2,370 3774.5 >10,000 >10,000 >10,000 Aripiprazole 1,081 5.6 8.7 22.4 642.4 9.97 25.85 74.1 37.63 2091.5 1,173.5 1.64 5.35 514 5.3 27.93 6,778 4,678 Asenapine ND 2.5 0.06 0.03 0.25 0.13 1.2 1.2 1.2 ND 1.4 1.3 0.42 1.1 0.0462 1.0 8,128 8,128 Blonanserin ND 804 0.812 26.4 41.9 183 26.7 (RB) 530 (RC) ND ND 1,070 0.142 0.494 150 5.72 765 100 ND N-DEBN ND ND 1.28 4.50 5.03 206 (RC) ND ND ND ND 1,020 1.38 0.23 ND 0.93 ND ND ND Chlorpromazine 1,296 2,115.5 4.5 15.6 17.0 28.4 0.28 184 46 2,443 76.3 1.40 4.65 5.33 3.21 3.09 32.3 57.0 Clozapine 1,624 123.7 5.35 9.44 13.5 17.95 1.62 37 6.0 3,168 266.3 157 269.1 26.4 0.0341 1.13 6.17 19.25 Norclozapine 316.6 13.9 10.9 11.9 (RC) 11.6 60.1 104.8 137.6 117.7 493.9 14.3 94.5 153 63.94 0.115 3.4 67.6 95.7 cis-Flupenthixol ND 8,028 87.5 (HFC) 102.2 (RC) ND ND ND ND ND ND 3.5 0.35 1.75 66.3 250 0.86 ND ND Fluphenazine 5,950 1,039.9 37.93 982.5 34.67 8.00 6.45 314.1 28.9 3,076 17.33 0.30 1.75 40.0 126.4 14.15 1,095 1,441 Haloperidol 3,256 2,066.83 56.81 4,801 5,133 377.6 12.0 801.5 403 2,112 121.8 0.7 3.96 2.71 81.2 1698 >10,000 >10,000 Iloperidone ND 93.21 1.94 147 63.09 112 0.3 160 16.2 1479 129.32 10.86 10.55 13.75 0.179 12 4,898 >10,000 Loxapine >10,000 2,456 6.63 13.25 31.0 87.6 31.0 150.9 80.0 5,698 54 28.1 19.33 7.80 0.236 4.90 119.45 211.33 Amoxapine 58 ND 0.5 2.0 (RC) 50 40.21 50 ND ND 16 ND 20.8 21.0 21.0 0.0240 25 1,000 1,000 Lurasidone ND 6.8 2.0 415 ND 0.5 48 1.6 10.8 ND 262 1.7 ND ND 1.18 >10,000 >10,000 >10,000 Melperone ND 2,200 (HB) 230 2,100 (HB) 1,254 (RC) 578 (HB) 180 (HB) 150 (HB) ND ND ND 194 8.95 555 1.186 580 >10,000 >10,000 Molindone ND 3,797 3773 >10,000 1,008 3,053 2,612 1,097 172.6 ND ND 6.0 72.5 2,950 628.83 2,130 ND >10,000 Olanzapine 3,676 2282 3.73 10.2 8.07 105.2 112 314 28.9 >10,000 70.33 34.23 47.0 14.33 0.109 2.19 2.5 56.33 Paliperidone 3,717 616.6 0.71 48 2,414 2.7 2.5 17.35 7.35 >10,000 41.04 0.7 0.5 54.3 1.104 18.8 >10,000 >10,000 Perphenazine ND 421 5.6 132 17 23 10 810.5 85.2 ND ND 0.14 0.13 17 40 8 1,500 1,848 Pimozide ND 650 48.35 2,112 71 0.5 197.7 1,593 376.5 ND >10,000 1.45 0.25 1.8 33.34 692.2 800 (HB) 1,955 Prochlorperazine ND 5,900 (HC) 15 (HC) 122 148 (RC) 196 (RC) 23.8 (HB) 1,694.91 (HB) ND ND ND 0.65 2.90 5.40 23.1 18.86 (HB) 555.55 (HB) ND Quetiapine >10,000 394.2 912 1,843 948.75 307.6 22 3,630 28.85 >10,000 994.5 379 340 2,019 2.41 6.90 489 1631.5 Norquetiapine ND 45 48 107 ND 76 144 237 ND 12 99.8 (RC) 196 ND ND 0.245 3.5 38.3 (RC) ND Risperidone >10,000 422.88 0.17 12 2057.17 6.6 5 16.5 1.3 >10,000 243.53 3.57 2.0 4.66 0.0476 20.05 >10,000 >10,000 Sertindole ND 280 0.39 0.9 5.4 28 1.8 640 450 ND ND 2.35 2.30 4.92 0.166 130 >5,000 2,692 Sulpiride ND >10,000 >10,000 (RC) >10,000 (RC) 5,000 (RC) 4,000 (RC) >10,000 (RB) 4,893 (RB) ND ND >10,000 9.80 8.05 54 >1,000 >10,000 (RB) >10,000 (RB) >10,000 (RB) Thioridazine 1,259 144.35 27.67 53 57.05 99 3.15 134.15 74.9 842 94.5 2.20 1.50 6.00 12.58 16.5 12.8 29 Thiothixene 3,878 410.2 50 1355.5 245.47 15.25 11.5 79.95 51.95 >10,000 51 0.12 0.40 203 416.7 8 >10,000 >10,000 Trifluoperazine ND 950 74 378 144 290.8 24 653.7 391.5 ND ND 1.12 ND 38.1 66.07 63 ND 1,001 Ziprasidone 112 54.67 0.73 13 60.95 6.31 18 160 68 44 30 4.35 7.85 52.9 0.1678 62.67 >10,000 >10,000 Zotepine 151 470.5 2.7 3.2 6 12 7 208 106 530 71 25 6.4 18 0.108 3.21 18 73 Acronyms used: HFC - Human frontal cortex receptor RB - Rat brain receptor RC - Cloned rat receptor ND - No data HB - Human brain receptor HC - Human cortex receptor N-DEBN - N-deethylblonanserin

Pharmacokinetics

Pharmacokinetics

Drug Bioavailability t1/2 parent drug (active metabolite) Protein binding tmax Cmax Vd Excretion Routes of administration Metabolising enzymes Active metabolites Amisulpride 48% 12 hr 16% 3-4 hr 54±4 ng/mL 5.8 L/kg Faeces (20%), urine (50%, when given IV) Oral ? None Aripiprazole 87% (Oral), 100% (IM) 75 hr (94 hr) 99% 3-5 hr ? 4.9 L/kg Faeces (55%), urine (25%) Oral, IM (including depot) CYP2D6, CYP3A4 Dehydroaripiprazole Asenapine 35% (sublingual) 24 hr 95% 0.5-1.5 hr 4 ng/mL 20-25 L/kg Urine (50%), faeces (40%) Sublingual CYP1A2, UGT1A4, CYP2D6 None Blonanserin 55% 10.7-16.2 hr (single dosing), 67.9 hr (repeated dosing) ≥99.7% 1.5-2 hr 0.14-0.76 ng/mL (0.57 ng/mL for repeated dosing) 8560-9500 L Urine (59%), faeces (30%) Oral CYP3A4 N-deethylblonanserin Chlorpromazine 20% 30 hr 92-97% ? ? 20 L/kg Urine Oral, IM, IV CYP2D6 Several active metabolites Clozapine 50-60% 12 hr 97% 1.5-2.5 hr 102-771 ng/mL 4.67 L/kg Urine (50%), faeces (30%) Oral CYP1A2, CYP2D6, CYP3A4 Norclozapine Droperidol ? 2 hr (8-12 hr) Extensive 60 min (IM) ? 2 L/kg (adults), 0.58 L/kg (children) Urine (75%), faeces (22%) IM, IV ? None Flupentixol 40-55% (Oral) 35 hr ? 7 days (depot) ? 12-14 L/kg Urine Oral, IM (including depot) ? None Fluphenazine 2.7% (Oral) 14-16 hrs, 14 days (depot) ? 2 hr (Oral), 8-10 hr (depot) ? ? Urine, faeces Oral, IM (including depot) ? None Haloperidol 60-70% (Oral) 10-20 hrs (short-acting IM), 3 weeks (depot) 92% 2-6 hr (Oral), 10-20 mins (short-acting IM), 6–7 days (depot) ? 8-18 L/kg Urine (30%), faeces (15%) Oral, IM, IV CYP3A4 None Iloperidone 96% ? 95% 2-4 hr ? 1340-2800 L Urine (45-58%), faeces (20-22%) Oral CYP3A4, CYP2D6 None notable. Levomepromazine ? 30 hr ? 2-3 hr ? ? Urine, faeces IM, IV ? Methotrimeprazine sulfoxide Loxapine High 6-8 hr (Inhaled), 4-12 hr (Oral) 96.6% 2 mins (inhaled), 2 hr (oral), 5 hr (IM) 257 ng/mL (inhaled), 6-13 ng/mL (Oral) ? Urine (56-70%), faeces [Only oral data available] Oral, IM, Inhalation CYP1A2, CYP3A4, CYP2D6 Amoxapine (a tricyclic antidepressant), 7-OH loxapine, 8-OH loxapine Lurasidone 9-19% 18 hr 99% 1-3 hr ? 6173 L Urine (9%), faeces (80%) Oral CYP3A4 2 active Melperone 54% (Oral via syrup), 65% (Oral via tablets), 87% (IM) 2.1-6.4 hrs (Oral), 6.6±3.7 hrs (IM) 50% 1.6-2.4 hr (Oral, tablets), 1 hr (Oral, syrup) 1132±814 ng/mL (25 mg, orally), 2228-3416 ng/mL (50 mg, orally), 89539±37001 ng/mL (100 mg, orally) 9.9±3.7 L/kg (10 mg), 7±1.61 L/kg (20 mg) Urine (70% as metabolites, 5.5-10.4% as parent drug) Oral, IM ? None Olanzapine 87% (Oral) 30 hr 93% 6 hr (Oral), 15-45 min (short-acting IM), 7 days (depot) 4-20.4 mg/mL 1000 L Urine (57%), faeces (30%) Oral, IM (including depot) CYP1A2 None Paliperidone 28% (Oral) 23 hr (Oral), 25–49 days (IM) 74% 24 hr (Oral), 13 days (IM) 8.85-11.7 ng/mL 390-487 L Urine (80%), faeces (11%) Oral, IM (depot) CYP3A4, CYP2D6 None Periciazine ? 12 hr ? 2 hr 150 ng/mL ? Urine Oral ? ? Perospirone ? 1.9-2.5 hr 92% 1.5 hr 5.7 ng/mL ? Urine (0.4% as unchanged drug) Oral ? None Perphenazine ? 9-12 hr (10-19 hr) ? 1-3 hr; 2-4 hr (metabolite) 0.984 ng/mL; 0.509 ng/mL ? Urine, faeces Oral CYP2D6 7-OH perphenazine Pimozide 40-50% 55 hr ? 6-8 hr 4-19 ng/mL (dose-dependent) ? Urine Oral CYP3A4, CYP2D6 None Prochlorperazine 12.5% 6.8-9 hr High ? ? 12.9-17.7 L/hr Urine, bile Oral, IM, IV ? N-desmethylprochlorperazine Quetiapine 100% 6 hr (IR), 7 hr (XR); active metabolite: 12 hr 83% 1.5 hr (IR), 6 hr (XR) @ 250 mg q8hr 778 ng/mL (male), 879 ng/mL (female) 6-14 L/kg Urine (73%), faeces (20%) Oral CYP3A4 Norquetiapine (a norepinephrine reuptake inhibitor and 5-HT1A receptor partial agonist) Risperidone 70% 3-17 hr (24 hr) 90% (active metabolite: 77%) 3-17 hr ? 1-2 L/kg Urine (70%), faeces (14%) Oral, IM (including depot) CYP2D6 Paliperidone Sertindole ? 3 days 99.5% 10 hr ? 20 L/kg Urine (4%), faeces (46-56%) Oral CYP2D6 None Sulpiride 27±9% 8 hr 40% 3-6 hr ? 2.72±0.66 L/kg Urine, faeces Oral ? None Thioridazine ? 24 hr 95% ? ? ? ? Oral CYP2D6 None Tiotixene ? 24 hr 90% ? ? ? ? Oral CYP1A2 None Trifluoperazine ? 24 hr ? ? ? ? ? Oral ? None Ziprasidone 60% (Oral), 100% (IM) 7 hr (Oral), 2-5 hr (IM) 99% 6-8 hr (Oral), ≤60 mins (IM) ? 1.5 L/kg Faeces (66%), urine (20%) Oral, IM CYP3A4, CYP1A2 None Zotepine 7-13% 13.7-15.9 hr (12 hr) 97% 1-4 hr 31-240 10 L/kg Urine (17%) Oral CYP1A2, CYP3A4 Norzotepine (a norepinephrine reuptake inhibitor) Zuclopenthixol 49% 20 hr 98% 2-12 hr (mean: 4 hr) ? 20 L/kg Faeces, urine (10%) Oral, IM (including depot) CYP2D6 None

History

Advertisement for Thorazine (chlorpromazine) from the 1950s, reflecting the perceptions of psychosis, including the now-discredited perception of a tendency towards violence, from the time when antipsychotics were discovered

The original antipsychotic drugs were happened upon largely by chance and then tested for their effectiveness. The first, chlorpromazine, was developed as a surgical anesthetic. It was first used on psychiatric patients because of its powerful calming effect; at the time it was regarded as a non-permanent "pharmacological lobotomy". Lobotomy at the time was used to treat many behavioral disorders, including psychosis, although its effect was to markedly reduce behavior and mental functioning of all types. However, chlorpromazine proved to reduce the effects of psychosis in a more effective and specific manner than lobotomy, even though it was known to be capable of causing severe sedation. The underlying neurochemistry involved has since been studied in detail, and subsequent antipsychotic drugs have been discovered by an approach that incorporates this sort of information.

The discovery of chlorpromazine's psychoactive effects in 1952 led to greatly reduced use of restraint, seclusion, and sedation in the management of agitated patients, and also led to further research that resulted in the development of antidepressants, anxiolytics, and the majority of other drugs now used in the management of psychiatric conditions. In 1952, Henri Laborit described chlorpromazine only as inducing indifference towards what was happening around them in nonpsychotic, nonmanic patients, and Jean Delay and Pierre Deniker described it as controlling manic or psychotic agitation. The former claimed to have discovered a treatment for agitation in anyone, and the latter team claimed to have discovered a treatment for psychotic illness.

Until the 1970s there was considerable debate within psychiatry on the most appropriate term to use to describe the new drugs. In the late 1950s the most widely used term was "neuroleptic", followed by "major tranquilizer" and then "ataraxic". The first recorded use of the term tranquilizer dates from the early nineteenth century. In 1953 Frederik F. Yonkman, a chemist at the Swiss based Cibapharmaceutical company, first used the term tranquilizer to differentiate reserpine from the older sedatives. The wordneuroleptic was derived from the Template:Lang-el(neuron, originally meaning "sinew" but today referring to the nerves) and "λαμβάνω" (lambanō, meaning "take hold of"). Thus, the word means taking hold of one's nerves. This may refer to common side effects such as reduced activity in general, as well as lethargy and impaired motor control. Although these effects are unpleasant and in some cases harmful, they were at one time, along with akathisia, considered a reliable sign that the drug was working. The term "ataraxy" was coined by the neurologist Howard Fabing and the classicist Alister Cameron to describe the observed effect of psychic indifference and detachment in patients treated with chlorpromazine. This term derived from the Greek adjective "ἀτάρακτος" (ataraktos) which means "not disturbed, not excited, without confusion, steady, calm". In the use of the terms "tranquilizer" and "ataractic", medical practitioners distinguished between the "major tranquilizers" or "major ataractics", which referred to drugs used to treat psychoses, and the "minor tranquilizers" or "minor ataractics", which referred to drugs used to treat neuroses. While popular during the 1950s, these terms are infrequently used today. They are being abandoned in favor of "antipsychotic", which refers to the drug's desired effects. Today, "minor tranquilizer" can refer to anxiolytic and/or hypnotic drugs such as the benzodiazepines and nonbenzodiazepines which have some antipsychotic properties and are recommended for concurrent use with antipsychotics, and are useful for insomnia or drug-induced psychosis. They are powerful (and potentially addictive) sedatives.

Antipsychotics are broadly divided into two groups, the typical or first-generation antipsychotics and the atypical or second-generation antipsychotics. The typical antipsychotics are classified according to their chemical structure while the atypical antipsychotics are classified according to their pharmacological properties. These include serotonin-dopamine antagonists (seedopamine antagonist and serotonin antagonist), multi-acting receptor-targeted antipsychotics (MARTA, those targeting several systems), and dopamine partial agonists, which are often categorized as atypicals.

Antipsychotic drugs are now the top-selling class of pharmaceuticals in America, generating annual revenue of about $14.6 billion.

Society and culture

Sales

Antipsychotics are among the biggest selling and most profitable of all drugs, generating $22 billion in global sales in 2008. By 2003 in the US, an estimated 3.21 million patients received antipsychotics, worth an estimated $2.82 billion. Over 2/3 of prescriptions were for the newer more expensive atypicals, each costing on average $164 compared to $40 for the older types. By 2008, sales in the US reached $14.6 billion, the biggest selling drugs in the US by therapeutic class. The number of prescriptions for children and adolescents doubled to 4.4 million between 2003 and 2006, in part because of increases in diagnoses of bipolar disorder.

Formulations

Antipsychotics are sometimes administered as part of compulsory psychiatric treatment via inpatient (hospital) commitment or outpatient commitment. They may be administered orally or, in some cases, through long-acting (depot) injections administered in the dorsgluteal, ventrogluteal or deltoid muscle.

Controversy

According to The Guardian newspaper: "At the heart of years of dissent against psychiatry through the ages has been its use of drugs, particularly antipsychotics, to treat distress. Do such drugs actually target any "psychiatric condition"? Or are they chemical control—a socially-useful reduction of the paranoid, deluded, distressed, bizarre and odd into semi-vegetative zombies?"

Use of this class of drugs has a history of criticism in residential care. As the drugs used can make patients calmer and more compliant, critics claim that the drugs can be overused. Outside doctors can feel under pressure from care home staff. In an official review commissioned by UK government ministers it was reported that the needless use of anti-psychotic medication in dementia care was widespread and was linked to 1800 deaths per year. In the US, the government has initiated legal action against the pharmaceutical company Johnson & Johnson for allegedly paying kickbacks to Omnicare to promote its antipsychotic Risperidone (Risperdal) in nursing homes.

There is some controversy over maintenance therapy for schizophrenia. A review of studies about maintenance therapy concluded that long-term antipsychotic treatment was superior to placebo in reducing relapse in individuals with schizophrenia, although some of the studies were small. A review of major longitudinal studies in North America found that a moderate number of patients with schizophrenia were seen to recover over time from their symptoms, raising the possibility that some patients may not require maintenance medication. It has also been argued that much of the research into long-term antipsychotic maintenance may be flawed due to failure to take into account the role of antipsychotic withdrawal effects on relapse rates.

There has also been controversy about the role of pharmaceutical companies in marketing and promoting antipsychotics, including allegations of downplaying or covering up adverse effects, expanding the number of conditions or illegally promoting off-label usage; influencing drug trials (or their publication) to try to show that the expensive and profitable newer atypicals were superior to the older cheaper typicals that were out of patent. Following charges of illegal marketing, settlements by two large pharmaceutical companies in the US set records for the largest criminal fines ever imposed on corporations. One case involved Eli Lilly and Company's antipsychotic Zyprexa, and the other involved Bextra. In the Bextra case, the government also charged Pfizer with illegally marketing another antipsychotic, Geodon. In addition, Astrazeneca faces numerous personal-injury lawsuits from former users of Seroquel (quetiapine), amidst federal investigations of its marketing practices. By expanding the conditions for which they were indicated, Astrazeneca's Seroquel and Eli Lilly's Zyprexa had become the biggest selling antipsychotics in 2008 with global sales of $5.5 billion and $5.4 billion respectively.

Harvard medical professor Joseph Biederman conducted research on bipolar disorder in children that led to an increase in such diagnoses. A 2008 Senate investigation found that Biederman also received $1.6 million in speaking and consulting fees between 2000 and 2007 — some of them undisclosed to Harvard — from companies including makers of antipsychotic drugs prescribed for children with bipolar disorder. Johnson & Johnson gave more than $700,000 to a research center that was headed by Biederman from 2002 to 2005, where research was conducted, in part, on Risperdal, the company's antipsychotic drug. Biederman has responded saying that the money did not influence him and that he did not promote a specific diagnosis or treatment.

Pharmaceutical companies have also been accused of attempting to set the mental heath agenda through activities such as funding consumer advocacy groups.

External links

• Are atypical antipsychotics advantageous? - the case for, Australian Prescriber 2005 (note: pharmaceutical company conflict of interest statement at the end)
• Are atypical antipsychotics advantageous? - the case against, Australian Prescriber 2005
• First Generation Antipsychotics: An Introduction, Psychopharmacology Institute, 2012
• Bipolar Meds - The Antipsychotics, mcmanweb.com
• FDA Public Health Advisory - Public Health Advisory for Antipsychotic Drugs used for Treatment of Behavioral Disorders in Elderly Patients, fda.gov
• FROTA LH. Partial Agonists in the Schizophrenia Armamentarium. Tardive Dysphrenia: The newest challenge to the last generation atypical antipsychotics drugs? J Bras Psiquiatr 2003; Vol 52 Supl 1;14-24. Free full-text in Portuguese with Abstracts in English, medicina.ufrj.br
• Antipsychotic Medication - information from mental health charity The Royal College of Psychiatrists
• Template:Pt icon FROTA LH. Fifty Years of Antipsychotic Drugs in Psychiatry. "Cinqüenta Anos de Medicamentos Antipsicóticos em Psiquiatria." 1st ed; Ebook: CD-Rom/On-Line Portuguese, ISBN 85-903827-1-0, File .pdf (Adobe Acrobat) 6Mb, Informática, Rio de Janeiro, August 2003, 486pp., medicina.ufrj.br