- Related Topics:
- Clozapine
- risperidone
- phenothiazine
- haloperidol
- butyrophenone
- On the Web:
- National Center for Biotechnology Information - Antipsychotic Medications (Oct. 16, 2026)
antipsychotic drug
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What is an antipsychotic drug?
Antipsychotic drugs treat psychosis, a mental illness affecting cognitive processes, often causing delusions and hallucinations, with schizophrenia being the most known psychosis. These medications, also known as neuroleptics, can calm agitation, excitement, and violent behavior in people with psychoses, and relieve symptoms of schizophrenia, mania, and delirium. While not curative, they improve lucidity and reduce hallucinations, though side effects vary, including drowsiness, altered blood pressure, and movement issues. They work by affecting neurotransmitters like serotonin and dopamine in the brain.
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What conditions are antipsychotic drugs used to treat?
Antipsychotic drugs, also known as neuroleptics, are used to treat mental disorders, including schizophrenia, mania, and delirium. They can also be used with antidepressants to treat psychotic depression. These medications can alleviate agitation, excitement, and violent behavior in people with psychoses, and are often effective in reducing hallucinations and delusions. Antipsychotics can help improve a patient’s lucidity and make them more receptive to psychotherapy. Though these drugs are not curative, they can reduce the severity of symptoms, and help people with mental illness to function outside of the hospital.
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How do antipsychotic drugs work in the brain?
Antipsychotic drugs, also known as neuroleptics, are used to treat psychosis by alleviating agitation, excitement, and violent behavior. While the exact mechanism isn't fully understood, one theory suggests that these drugs influence neurotransmitters like serotonin and dopamine in the brain.
Most antipsychotics block dopamine receptors, reducing dopaminergic transmission in the forebrain, while atypical antipsychotics also affect serotonin receptors. By affecting these chemical messengers, antipsychotic drugs can control symptoms such as hallucinations and delusions and improve lucidity.
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What are the main types of antipsychotic drugs?
Antipsychotic drugs, or neuroleptics, come in two main types: typical and atypical. Typical antipsychotics, also known as first-generation antipsychotics, work by blocking dopamine receptors, and examples include haloperidol and chlorpromazine. Atypical antipsychotics, or second-generation antipsychotics, inhibit neurotransmitters like acetylcholine, serotonin, and [norepinephrine](www.britannica.com/science/psychotropic-drug/Introduction#ref1]; examples include clozapine, aripiprazole, and iloperidone. Risperidone, another atypical antipsychotic, blocks receptors in the brain that are responsive to serotonin and dopamine and is used to treat schizophrenia. These drugs can help to alleviate hallucinations and delusions, as well as improve lucidity.
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What are some common side effects of antipsychotic drugs?
Antipsychotic drugs, also known as neuroleptics, can cause several side effects, including drowsiness, altered blood pressure or heart rate, and movement issues such as tremors or slowness.
First-generation antipsychotics may result in extrapyramidal symptoms (EPS), such as Parkinson-like tremors, rigidity, dystonia, slowness of movement, akathisia, and tardive dyskinesia. While most EPS disappear when the drug is stopped, tardive dyskinesia can persist long-term, even after discontinuing the medication. Atypical antipsychotics may increase the risk of diabetes, high cholesterol, heart problems, and stroke and can elevate suicidal thoughts in patients under 18. Neuroleptic malignant syndrome, a rare but potentially fatal side effect, can also occur.
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How can doctors decide which antipsychotic drug is right for a patient?
Doctors consider several factors when choosing the right antipsychotic medication for a patient. No single drug is superior for treating schizophrenia. The choice depends on individual differences in how patients respond to the drugs and the severity of unwanted side effects.
Psychiatrists may switch to a different chemical group if one drug proves ineffective despite adequate dosage over several weeks. During an acute psychotic episode, drugs like olanzapine or haloperidol can have a calming effect within a couple of days, but it may take weeks to control psychotic symptoms like hallucinations or disordered thinking. The appropriate dosage is determined for each patient individually, cautiously increasing the dose until a therapeutic effect is achieved without unacceptable side effects.
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antipsychotic drug, any agent used in the treatment of psychosis, a form of mental illness. Psychoses can affect cognitive processes such as judgment and frequently cause delusions and hallucinations. The most widely known psychosis is schizophrenia. Effective treatments for some forms of schizophrenia have revolutionized thinking about the disease and have prompted investigations into its possible genetic origins and pathological causes. These investigations have also shed light on the mechanisms by which antipsychotic drugs may exert their effects.
The history of reserpine can be traced to an Indian shrub, called Rauwolfia serpentina for its snakelike appearance, which historically was used to treat snake bites, insomnia, high blood pressure, and mental illness. Reserpine, the principal alkaloid of the plant, was first isolated in the 1950s and was used in the treatment of hypertension (high blood pressure diagnosed clinically). It was later given to persons with schizophrenia, in whom the drug was found to act as a behavioral depressant. In fact, the depression of patients given the drug for hypertension was a major side effect. The basic mechanisms of action of reserpine in producing depression are attributed to its ability to deplete the brain’s stores of the neurotransmitters serotonin and norepinephrine.
The second major class of antipsychotic drugs, the phenothiazines, arose from modifications of the dye methylene blue, which was under investigation as an antagonist of histamine. Attempts to modify this series to increase their activity in the central nervous system and reduce the need for surgical anesthetics ultimately led to the first effective drug of this class, chlorpromazine. Its ability to stabilize behaviour and to improve lucidity as well as to reduce hallucinatory behaviour was recognized within a few years of its introduction in the mid-1950s. The use of chlorpromazine changed the role of the mental hospital and resulted in the large-scale, perhaps excessive, discharge of persons with schizophrenia into the outside world.
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A third class of antipsychotics, the butyrophenones, emerged when a small Belgian drug company embarked on a plan in the late 1950s to develop analogs of meperidine through inexpensive chemical substitutions. Experiments gave rise to a compound that caused chlorpromazine-like sedation but had a completely different structure. This led to the compound haloperidol, a more powerful antipsychotic with relatively fewer side effects.
A fourth class of drugs, commonly known as “atypicals” but more properly called atypical antipsychotics or serotonin-dopamine antagonists, is related to chlorpromazine and to haloperidol. These antipsychotics can improve both the so-called positive symptoms (e.g., hallucinations, delusions, and agitation) and the negative symptoms of schizophrenia, such as catatonia and flattening of the ability to experience emotion. Each agent in this group has a unique profile of receptor interactions. Virtually all antipsychotics block dopamine receptors and reduce dopaminergic transmission in the forebrain. The atypical antipsychotics also have affinity for serotonin receptors.
The major acute side effects of chlorpromazine and haloperidol are oversedation and a malaise that makes the drugs poorly received by the patient and makes compliance with chronic self-medication difficult. Prolonged treatment of middle-aged and even young adults with antipsychotic drugs can evoke serious movement disorders that in part resemble Parkinson disease, a degenerative condition of the nerves. First to appear are tremors and rigidity, and those are followed by more complex movement disorders commonly associated with involuntary twitching movements on the arms, lips, and tongue, called tardive dyskinesia. The atypical antipsychotics do not produce the movement disorders that are seen with the use of the older drugs, probably because of their affinity for both serotonin and dopamine receptors. None of the antipsychotics is curative, because none eliminates the fundamental disorder of thought processes.
Neuroleptic malignant syndrome is a rare, potentially fatal neurological side effect of antipsychotic drug use. Individuals develop a severe rigidity with catatonia, autonomic instability, and stupor, which may persist for more than one week. Neuroleptic malignant syndrome has occurred with all antipsychotics, but the disorder is more common with relatively high doses of more potent agents such as haloperidol.
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