SulfonesPurinesPiperazinesPhosphodiesterase InhibitorsPhosphodiesterase 5 Inhibitors3',5'-Cyclic-GMP PhosphodiesterasesErectile DysfunctionCyclic Nucleotide Phosphodiesterases, Type 5Administration, OralPenile ErectionHomosexuality, MaleMethamphetamineVasodilator AgentsDouble-Blind MethodCyclic GMPArea Under CurveHalf-LifeGeorgiaCross-Over StudiesDose-Response Relationship, DrugDrug Administration ScheduleBiological AvailabilityUnsafe SexRisk-TakingDrug InteractionsSexual BehaviorFood-Drug InteractionsInjections, IntravenousTime FactorsTreatment OutcomeMetabolic Clearance RateQuinolinesPlacebosAnti-Infective AgentsChromatography, High Pressure LiquidHealthy VolunteersInfusions, IntravenousDelayed-Action PreparationsRadiation DosageFluoroquinolonesLethal Dose 50QuinolonesAcetamidesCiprofloxacinInjections, IntramuscularCapsulesOxazolidinonesDrug Therapy, CombinationSerum Bactericidal TestAza CompoundsTabletsIntestinal AbsorptionDrug ToleranceBlisterButyrophenonesBiotransformationCilazaprilAntineoplastic AgentsTriazolamHypnotics and SedativesRandom AllocationRadiometrySucralfateAnti-Anxiety AgentsDrug Dosage CalculationsTherapeutic EquivalencyThiophenesDrug EvaluationCephalosporinsAnti-Bacterial AgentsPiperidinesOfloxacinPyrrolidinesAbsorptionAdministration, InhalationOndansetronKetoconazoleNebulizers and VaporizersGas Chromatography-Mass SpectrometryCytochrome P-450 CYP3ADrug CombinationsSafetyPyridazinesIndolesLevofloxacinAnalysis of VarianceNauseaAntacidsDose-Response Relationship, RadiationAntibodies, MonoclonalPyrrolesClinical Trials as TopicNaphthyridinesDose FractionationNeoplasmsBlood PressurePyridinesRadiotherapy DosageHeart RateChemistry, Pharmaceutical