Clozapin

Clozapin is an atypical antipsychotic medication used to treat certain psychiatric conditions, most notably schizophrenia that has not responded adequately to other antipsychotic treatments. It is also employed for schizoaffective disorder in some settings and has a specific indication for reducing the risk of suicide in schizophrenia in certain countries.

Clozapin works by blocking several neurotransmitter receptors, including dopamine D2 and serotonin 5-HT2A receptors, as well as other receptor systems such as muscarinic and adrenergic receptors. This broad receptor profile contributes to its unique therapeutic effects, particularly in treatment-resistant cases where other antipsychotics have failed. Clozapin has demonstrated efficacy in reducing positive symptoms and some negative symptoms, and it is associated with a lower risk of tardive dyskinesia compared with some older antipsychotics. Its approved use for reducing suicidality in schizophrenia is a notable aspect of its profile.

Due to a risk of serious adverse effects, clozapin requires careful medical oversight. Treatment typically begins with a low dose and gradual titration. Patients must undergo regular blood monitoring to detect agranulocytosis and neutropenia; in many health systems this includes a structured schedule of white blood cell and absolute neutrophil count testing, often with enrollment in a monitoring program. Clozapine can also cause sedation, weight gain, metabolic changes, hypersalivation, constipation that can lead to serious bowel complications, tachycardia, and, less commonly, myocarditis and seizures. Drug interactions and factors such as smoking can alter clozapine levels.

Historically, clozapine was withdrawn from some markets due to safety concerns but was reintroduced with stringent monitoring. It is generally regarded as a treatment option after other antipsychotics have failed to provide adequate benefit, and its use is guided by regional regulatory approvals and clinical guidelines.