CYP2D6 poor metabolizer status significantly affects the clinical outcome with which of the following beta-blockers due to accumulation of active parent drug?

• A Atenolol
• B Nadolol
• C Carteolol
• D Metoprolol ✓

Explanation

Metoprolol is extensively metabolised by CYP2D6 to inactive metabolites (alpha-hydroxymetoprolol and O-demethylmetoprolol). CYP2D6 poor metabolizers (about 7-10% of Caucasians, ~1-2% South Asians) accumulate parent metoprolol, resulting in pronounced beta-blockade, bradycardia, and hypotension at standard doses. Atenolol and nadolol are hydrophilic and largely renally excreted, not dependent on CYP2D6. This pharmacogenomic distinction is clinically important when selecting beta-blockers in patients on CYP2D6 inhibitors such as fluoxetine.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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