Antipsychotics

Antipsychotics are a class of medicines used to treat psychotic disorders, most notably schizophrenia, bipolar disorder with manic episodes, and severe agitation or delirium. They work mainly by blocking dopamine D2 receptors in the brain, which can reduce positive symptoms such as hallucinations and delusions. Atypical antipsychotics also antagonize serotonin 5-HT2A receptors, a combination that can lower the risk of movement disorders and may help with negative symptoms and mood symptoms.

Antipsychotics are broadly divided into typical (first-generation) and atypical (second-generation) drugs. Typical antipsychotics, such as haloperidol and chlorpromazine, are often potent D2 antagonists with a higher risk of extrapyramidal symptoms and tardive dyskinesia. They remain useful for acute agitation, schizophrenia, and certain stimulant-induced psychoses.

Atypical antipsychotics—risperidone, olanzapine, quetiapine, ziprasidone, aripiprazole, and clozapine—tend to have broader receptor profiles and lower EPS risk, but they carry metabolic risks including weight gain, diabetes, and dyslipidemia. Clozapine is reserved for treatment-resistant cases but requires routine blood monitoring due to agranulocytosis.

Common side effects include EPS (parkinsonism, akathisia), tardive dyskinesia, sedation, dry mouth, constipation, and anticholinergic effects. Prolactin elevation with many D2 antagonists can cause galactorrhea and menstrual disturbances. Some agents prolong the QT interval. Clozapine carries the risk of agranulocytosis and severe neutropenia, necessitating regular blood counts.

Use in the elderly with dementia-related psychosis is associated with higher mortality. Monitoring guidelines recommend baseline weight, glucose, lipids, and blood pressure, as well as regular follow-up for movement disorders and metabolic effects. Dosing and choice depend on diagnosis, prior response, side-effect profile, and monitoring requirements.