- Current use of the following drugs: amiodarone; anticoagulants (e.g., warfarin); anti-retroviral therapy (e.g., ritonavir); carbamazepine; chlorpromazine; cisapride; clarithromycin; clopidogrel; disopyramide; droperidol; erythromycin; fondaparinux; haloperidol; heparin; itraconazole; ketoconazole