Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.
Metoprolol is a beta blocker that acts mainly on the heart (beta-1 selective): it blocks the effect of adrenaline there, slowing the heart rate and lowering blood pressure. It is used for high blood pressure, angina, some irregular heart rhythms, after a heart attack, for heart failure and to prevent migraine. It is sold as Lopressor and, as an extended-release form, Toprol-XL, among other names.
Metoprolol is broken down mainly by the liver enzyme CYP2D6. People with no working CYP2D6 copies (poor metabolizers) have several times higher blood levels, and studies find a slower heart rate in them; people with extra copies clear it faster. CPIC and DPWG have published guidelines on CYP2D6 and metoprolol, and the US FDA lists an effect on drug levels. Studies have also looked at the drug's targets, the beta-adrenergic receptor genes ADRB1 and ADRB2, and at GRK4, with weaker evidence.
Clinical guidelines that name a gene for Metoprolol. They sort people into groups by the gene copies they carry.
CPIC guideline: CYP2D6. CYP2D6 activity score 0 to 6 or more. Strong. 2024.
DPWG guideline: CYP2D6. CYP2D6 activity score 0 to 6 or more. 2011.
Every published finding on gene variants and Metoprolol. 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.
CYP2D6 CYP2D6*1, CYP2D6*2, CYP2D6*3, CYP2D6*4, CYP2D6*5, CYP2D6*6, CYP2D6*9, CYP2D6*10, CYP2D6*17, CYP2D6*29, CYP2D6*31, CYP2D6*35, CYP2D6*41: Level 1A · replicated. Metabolism/PK: Hypertension. 12.
CYP2D6 CYP2D6*1, CYP2D6*4: Level 1A · replicated. Dosage: Heart Failure. 2.
ADRB1 rs1801253: Level 3. Efficacy. 11.
ADRB1 rs1801252: Level 3. Efficacy: Hypertension. 4.
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
Beta Blockers (class) (Beta 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.
Content updated September 2026.
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