Verapamil (Calan)

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

About Verapamil

What it is

Verapamil is a calcium channel blocker that acts on both the heart and blood vessels: it slows the heart rate and the conduction of the heartbeat, and relaxes arteries. It is used for high blood pressure, angina, to slow fast heart rhythms such as atrial fibrillation, and to prevent cluster headaches. It is sold as Calan, Isoptin and Verelan, among other names.

How genes come into it

Verapamil is broken down mainly by CYP3A4 and blocks both CYP3A4 and the transporter ABCB1 itself, so it interacts with many other medicines. Most gene studies on it come from a large blood pressure trial (INVEST) and looked at genes such as NR1H3, KCNMB1, the calcium channel gene CACNA1C and ADRB1 for blood pressure response and outcomes. The findings come from single or a few studies, and there is no CPIC or DPWG guideline.

What research found

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

Rated evidence (13 rated variants)

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

KCNIP1;KCNMB1 rs11739136: Level 3. Efficacy: Hypertension. 3.

KCNIP1;KCNMB1 rs2301149: Level 3. Efficacy: Coronary Artery Disease, Hypertension. 1.

ABCB1 rs1045642: Level 3. Other. 1.

ABCB1 rs2032582: Level 3. Other. 1.

Metabolism (2 findings)

Studies of how quickly the body processes this medication.

ABCB1 rs1045642: Genotype GG is associated with decreased metabolism of verapamil in healthy individuals as compared to genotypes AA + AG.

ABCB1 rs2032582: Genotype CC is associated with decreased metabolism of verapamil in healthy individuals as compared to genotypes AA + AC.

Response (11 findings)

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

ADRB1 rs1801253: Genotypes CG + GG are associated with increased response to atenolol, carvedilol, diltiazem, metoprolol or verapamil in people with Atrial Fibrillation as compared to genotype CC.

ITGAL rs2230433: Allele C is associated with increased clinical benefit to verapamil in people with Migraine NOS as compared to allele G.

PCDHB6 rs17844444: Allele A is associated with decreased clinical benefit to verapamil in people with Migraine NOS as compared to allele G.

PCDHB8 rs3733694: Allele G is associated with decreased clinical benefit to verapamil in people with Migraine NOS as compared to allele A.

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

Calcium Channel Blockers (class) (Calcium Channel Blockers)

Cardene (Calcium Channel Blockers)

Cardizem (Calcium Channel Blockers)

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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