- Use of nitrates, alfa blockers, vasodilators, ketoconazole, itraconazole, ritonavir, saquinavir, telithromycin, nefazodone, nelfinavir, atazanavir, cimetidine, erythromycin, clarithromycin, fluconazole, amprenavir, fosamprenavir, aprepitant, verapamil, diltiazem, any kind of vasodilator, antiplatelet, anticoagulant, dapoxetine, phosphodiesterase 5 inhibitor, alcohol and stimulant drug,