A 55-year-old woman with type 2 diabetes on repaglinide develops hypoglycemia after starting clarithromycin for a respiratory infection. Repaglinide is metabolized primarily by which cytochrome P450 enzyme, inhibition of which explains this interaction?

• A CYP2D6
• B CYP2C19
• C CYP2C9
• D CYP3A4 ✓

Explanation

Repaglinide is metabolized primarily by CYP3A4 and to a lesser extent CYP2C8. Clarithromycin is a potent CYP3A4 inhibitor, increasing repaglinide levels and causing hypoglycemia. CYP2C9 metabolizes glipizide. CYP2B6 and CYP2C19 are not the primary enzymes for repaglinide. This drug interaction is well described in Katzung.

Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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