Clopidogrel should be used with caution in patients receiving other drugs that increase the risk of bleeding, including anticoagulants, other antiplatelets and NSAIDs. Clopidogrel may inhibit the cytochrome P450 isoenzyme CYP2C9 and interactions with drugs metabolized by this isoenzyme are theoretically possible; it may also inhibit CYP2B6 as was observed with the reduced conversion of bupropion to its active metabolite.