Chlorpromazine (Thorazine)

Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.

About Chlorpromazine

What it is

Chlorpromazine was the first antipsychotic, introduced in the early 1950s, and changed the treatment of schizophrenia. A phenothiazine, it blocks dopamine D2 receptors and many others. It is still used for schizophrenia and mania, severe agitation, persistent hiccups and nausea. It is sold as Thorazine and Largactil, among other names.

How genes come into it

Chlorpromazine is broken down mainly by CYP1A2 and CYP2D6. The few gene studies listing it looked at the dopamine receptor gene DRD2, EPM2A and MTHFR for response. The findings come from a few studies, and there is no CPIC or DPWG guideline.

What research found

Every published finding on gene variants and Chlorpromazine. Upload your DNA file to see which of these rows apply to you.

Rated evidence (1 rated variant)

PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.

EPM2A rs1415744: Level 3. Efficacy: Schizophrenia. 1.

Response (3 findings)

Studies of how well it worked in people carrying a variant.

DRD2 rs1799732: Genotype GG is associated with increased response to chlorpromazine in people with Schizophrenia as compared to genotypes G/del + del/del.

EPM2A rs1415744: Allele C is associated with increased response to chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone or trifluoperazine in people with Schizophrenia as compared to allele T.

MTHFR rs1801133: Genotype AG is associated with decreased clinical benefit to antipsychotics, chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine or risperidone in women with Schizophrenia as compared to genotype GG.

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.

Related Drugs

More drugs from the same category

Abilify (Antipsychotics)

Antipsychotics (class) (Antipsychotics)

Bromperidol (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.

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Content updated September 2026.

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