Penile ErectionSulfonesPurinesPenisErectile DysfunctionPhosphodiesterase 5 InhibitorsPiperazinesPhosphodiesterase InhibitorsPriapismCyclic Nucleotide Phosphodiesterases, Type 5CanadaImpotence, Vasculogenic3',5'-Cyclic-GMP PhosphodiesterasesVasodilator AgentsOrgasmLibidoPenile IndurationEjaculationPapaverineAlprostadilCarbolinesContraceptives, OralHypertension, PulmonaryApomorphineCoitusCyclic GMPTriazinesContraceptives, PostcoitalAdministration, OralContraceptives, Oral, CombinedTreatment OutcomeTime FactorsPenile ProsthesisAphrodisiacsNitric OxidePenile ImplantationClitorisYawningContraceptives, Oral, HormonalNepetaSexual Dysfunction, PhysiologicalDouble-Blind MethodInjectionsUrologic Surgical Procedures, MaleDose-Response Relationship, DrugCopulationPhentolamineCross-Over StudiesNitric Oxide Synthase Type IOntarioRats, Sprague-DawleyPhosphoric Diester HydrolasesQuestionnairesContraception, PostcoitalPyrimidinonesErgoloid MesylatesContraception BehaviorPressureContraceptive Agents, FemalePatient SatisfactionBlood PressurePulmonary ArteryHypogonadismNG-Nitroarginine Methyl EsterTestosteroneNitric Oxide SynthasePlacebosContraceptionPenile DiseasesNitric Oxide DonorsUrethraMethoxamineRats, WistarAlbertaDopamine AgonistsMuscle, SmoothDrug Interactions