SulfonesPurinesCanadaPiperazinesPhosphodiesterase InhibitorsPhosphodiesterase 5 Inhibitors3',5'-Cyclic-GMP PhosphodiesterasesErectile DysfunctionCyclic Nucleotide Phosphodiesterases, Type 5Homosexuality, MalePenile ErectionMethamphetamineVasodilator AgentsCyclic GMPGeorgiaUnsafe SexOntarioRisk-TakingSexual BehaviorBritish ColumbiaAlbertaQuebecManitobaNova ScotiaNorthwest TerritoriesSaskatchewanNunavutYukon TerritoryNewfoundland and LabradorInuitsPrince Edward IslandTime FactorsArctic RegionsNew BrunswickReproducibility of ResultsQuestionnairesMolecular Sequence DataSingle-Payer SystemIndians, North American