Always ensure you tell your healthcare provider about other medicines you are making use of presently -such as HIV protease inhibitors, erythromycin, particular antifungals, amlodipine, barbiturates, 'beta' blockers, anticoagulants, bosentan, various other erectile dysfunction meds, efavirenz, rifabutin, alpha blockers, seizure medicines, nevirapine, rifampin, medications for hypertension, or cimetidine.