CYP3A4 is the most abundant hepatic CYP enzyme and is responsible for metabolising approximately 50% of drugs. Which drug is a potent inducer of CYP3A4?

• A Ketoconazole
• B Erythromycin
• C Grapefruit juice components
• D Rifampicin ✓

Explanation

Rifampicin is one of the most potent inducers of CYP3A4 (and other CYPs), activating the pregnane X receptor (PXR), which upregulates CYP gene transcription, leading to accelerated metabolism of co-administered drugs. Ketoconazole and erythromycin are CYP3A4 inhibitors. Grapefruit furanocoumarins (bergamottin) irreversibly inhibit intestinal CYP3A4, increasing oral bioavailability of certain drugs.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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