TramadolPremature EjaculationTabletsAnalgesics, OpioidTherapeutic EquivalencyAdministration, OralDelayed-Action PreparationsChemistry, PharmaceuticalTablets, Enteric-CoatedCross-Over StudiesDouble-Blind MethodBiological AvailabilityDrug Administration ScheduleExcipientsAnti-Inflammatory Agents, Non-SteroidalDrug CompoundingDose-Response Relationship, DrugChromatography, High Pressure Liquid