A patient is of warfarin therapy. All of the following drugs increase the risk of bleeding with warfarin except?
(A) Isoniazid (B) Amiodarone (C) Carbamazepine (D) Cimetidine
(C) Warfarin (anti-coagulant) is metabolized by microsomal enzymes. So, enzyme inducer decreases its effects whereas enzyme inhibitors lead to its toxicity. Enzyme inhibitors include valproate, ketoconazole, cimetidine, ciprofloxacin, erythromycin, isoniazid, amiodarone etc. These can increase the risk of bleeding with warfarin. Carbamazepine is an enzyme inducer, it decrease the effect of warfarin.