SulfonesPurinesPiperazinesPhosphodiesterase InhibitorsPhosphodiesterase 5 Inhibitors3',5'-Cyclic-GMP PhosphodiesterasesErectile DysfunctionGelsCyclic Nucleotide Phosphodiesterases, Type 5Penile ErectionHomosexuality, MaleMethamphetamineVasodilator AgentsCyclic GMPGeorgiaUnsafe SexElectrophoresis, Gel, Two-DimensionalRisk-TakingSexual BehaviorElectrophoresis, Gel, Pulsed-FieldElectrophoresis, Agar GelMolecular Sequence DataIsoelectric FocusingVaginal Creams, Foams, and JelliesBase SequenceElectrophoresisKineticsDenaturing Gradient Gel Electrophoresis