Question

Which of the following drugs, when given with warfarin, induces hepatic CYP450 enzyme?

• A. Ciprofloxacin
• B. Metronidazole
• C. Carbamazepine
• D. Diltiazem

Hint:

CYP450 inducers like carbamazepine, rifampin, and phenytoin reduce warfarin levels. In contrast, inhibitors like ciprofloxacin and metronidazole increase warfarin’s effects.

Answer 1

The Correct Option is C

The question asks which drug speeds up, rather than slows down, warfarin's breakdown by liver enzymes.

1. Ciprofloxacin: Blocks CYP450 activity, raising warfarin levels, which is enzyme inhibition, not induction.
2. Metronidazole: Also blocks the CYP2C9 enzyme central to warfarin metabolism, again raising its level rather than lowering it.
3. Carbamazepine: Ramps up CYP3A4 activity, clearing warfarin from the body faster and reducing its blood concentration, exactly the induction effect the question is looking for.
4. Diltiazem: Inhibits CYP3A4, slowing warfarin clearance and raising its level, the opposite of induction.

Carbamazepine is the one drug here that induces, rather than inhibits, the enzymes that clear warfarin.

So the correct answer is Carbamazepine.