Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.
Clozapine is an antipsychotic used for schizophrenia when other antipsychotics have not helped, and to lower the risk of suicidal behaviour in schizophrenia. It acts on many receptors at once, including dopamine and serotonin receptors. Because it can rarely cause a dangerous fall in white blood cells, regular blood counts are part of treatment. It is sold as Clozaril and FazaClo, among other names.
Clozapine is broken down mainly by the liver enzyme CYP1A2, with help from CYP2D6, CYP2C19 and CYP3A4. CYP1A2 activity is strongly affected by smoking, which speeds it up, and studies have looked at CYP1A2 variants too. The US drug label mentions CYP2D6 poor metabolizers, who may have higher levels, and the US FDA lists this pair; there is no CPIC or DPWG guideline. Studies have also looked at dopamine and serotonin receptor genes for response and side effects such as weight gain, with weaker evidence.
Clinical guidelines that name a gene for Clozapine. They sort people into groups by the gene copies they carry.
US FDA: CYP2D6. CYP2D6 activity score 0.
US FDA: CYP2D6. CYP2D6 activity score 0. Data that Support Therapeutic Management Recommendations.
Every published finding on gene variants and Clozapine. Upload your DNA file to see which of these rows apply to you.
PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.
CYP1A2 rs762551: Level 3. Metabolism/PK. 6.
HTR2C rs1414334: Level 3. Toxicity: Metabolic Syndrome, Schizophrenia. 5.
HTR2C rs3813929: Level 3. Toxicity: Mental Disorders, Schizophrenia. 5.
ABCB1 rs1045642: Level 3. Toxicity. 2.
Studies of how quickly the body processes this medication.
Studies of how well it worked in people carrying a variant.
Studies of how much of the drug people needed or tolerated.
Studies of side effects in people carrying a variant.
Studies that do not fall into the groups above.
Study findings and evidence levels: PharmGKB (CC BY-SA 4.0). Guidelines: CPIC and DPWG, as bundled in PharmCAT. Most studies were done mainly in people of European ancestry.
More drugs from the same category
Antipsychotics (class) (Antipsychotics)
Not a prescribing recommendation. This page is educational information about pharmacogenomic research and clinical guidelines - it is not medical or dosing advice, and not a prediction of how any medication will work for you. Never start, stop, or change a medication or dose based on it; talk to your doctor or pharmacist, who can order clinical-grade testing if appropriate.
Content updated September 2026.
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