SulfonesPurinesDouble-Blind MethodClinical Trials as TopicTreatment OutcomePiperazinesPhosphodiesterase 5 InhibitorsDrug Therapy, CombinationDose-Response Relationship, DrugDrug Administration SchedulePhosphodiesterase InhibitorsTime FactorsPilot ProjectsImmunosuppressive AgentsCyclic Nucleotide Phosphodiesterases, Type 5Follow-Up StudiesProspective StudiesDisease Models, AnimalErectile DysfunctionRetrospective Studies3',5'-Cyclic-GMP PhosphodiesterasesVasodilator AgentsPenile ErectionHypertension, PulmonaryImpotence, VasculogenicCarbolinesAdministration, OralCyclic GMPPenisTriazinesPyrimidinonesPhosphoric Diester HydrolasesPulmonary ArteryCross-Over StudiesPriapismDrug-Related Side Effects and Adverse ReactionsNitric OxideVascular ResistanceClitorisCyclic GMP-Dependent Protein KinasesBlood PressureHypertrophy, Right VentricularPulmonary Wedge PressureIloprostHemodynamicsAntihypertensive AgentsDrug InteractionsDihydroergocristineEjaculationPapaverinePlacebosAlprostadilDrug SynergismRats, WistarSulfonamidesEpimediumPentylenetetrazoleImidazolesCyclic Nucleotide Phosphodiesterases, Type 2PainHeart RatePatient SatisfactionAntipsychotic AgentsGuanylate CyclaseAnalgesics, OpioidRats, Sprague-DawleyVasodilationCoitusSafetyPulmonary CirculationEpoprostenolHeadacheEsophageal Motility DisordersOrgasmMice, Inbred ICRCREST SyndromeAnalgesicsDelayed-Action PreparationsMilrinoneMonocrotalineLibidoDrug CombinationsExercise TestDoxazosinInjectionsMagnesium HydroxideNG-Nitroarginine Methyl EsterEnzyme InhibitorsExercise ToleranceRegional Blood FlowPurinonesCardiomyopathy, RestrictiveInjections, SpinalCyclic GMP-Dependent Protein Kinase Type IRandom AllocationNauseaNitric Oxide DonorsPain MeasurementPentaerythritol TetranitrateIsosorbide Dinitrate