Clozapine

Clozapine is a psychiatric medication and is the first atypical antipsychotic (also called second-generation antipsychotic) to be discovered. It is primarily used to treat people with schizophrenia and schizoaffective disorder who have had an inadequate response to two other antipsychotics or who have been unable to tolerate other drugs due to extrapyramidal side effects. It is also used for the treatment of psychosis in Parkinson's disease.

Clozapine is recommended by multiple international treatment guidelines, after resistance to two other antipsychotic medications and is the only treatment likely to result in improvement if two (or one) other antipsychotic has not had a satisfactory effect. Long term follow-up studies from Finland show significant improvements in terms of overall mortality including from suicide and all causes. Clozapine is on the World Health Organization's List of Essential Medicines. It is available as a generic medication and so it is not usually promoted by pharmaceutical companies. Common adverse effects include drowsiness, constipation, hypersalivation (increased saliva production), tachycardia, low blood pressure, blurred vision, weight gain, and dizziness. Clozapine is not normally associated with tardive dyskinesia (TD) and is recommended as the drug of choice when this is present, although some case reports describe clozapine-induced TD. Potential adverse effects include agranulocytosis, seizures, myocarditis (inflammation of the heart), hyperglycemia (high blood glucose levels), and constipation. The use of this drug can rarely result in clozapine-induced gastric hypomotility syndrome which may lead to bowel obstruction and death, and in older people with psychosis, as a result of dementia it may lead to an increased risk of death. The mechanism of action is not entirely clear in the current medical literature.