PapaverinePapaverVasodilator AgentsPenile ErectionThebainePhosphodiesterase InhibitorsChlorobutanolInfusions, Intra-ArterialAdministration, OralPharmaceutical SolutionsVasospasm, IntracranialOpiumErectile DysfunctionPenisParasympatholyticsTheophyllineCinnarizineCapillary ElectrochromatographyDose-Response Relationship, Drug