ABSTRACT
Co-administration of tadalafil and tamsulosin HCl in patients with benign prostate hyperplasia and erectile dysfunction is increasing in clinical settings. Development of fixed-dose combination (FDC) of tadalafil and tamsulosin HCl could contribute to improving patients' adherence and treatment efficacy. We evaluated the pharmacokinetics and safety profiles of a newly developed fixed-dose combination capsule of tadalafil 5 mg/tamsulosin HCl 0.4 mg in comparison with co-administration of each formulation in healthy volunteers under fasted and fed conditions. Two randomized, open-label, single-dose, two-way, crossover studies were completed in 29 subjects under fasted condition, and 33 subjects under fed condition. Serial blood sample collection for PK analysis was conducted up to 72 hours after dosing, and PK parameters were calculated using non-compartmental analysis. Geometric mean ratios and 90% confidence intervals of the C(max) and AUC(last) were used to evaluate comparative bioavailability. In both fasted and fed condition studies, the bioequivalence was established. The most common adverse drug reactions were orthostatic hypotension and headache with no statistical difference between treatment groups. All subjects with orthostatic hypotension recovered at follow-up test. Although changes in vital signs from baseline were statistically significant, there were no subjects with systolic blood pressure < 90 mmHg and there were no clinically meaningful signs or symptoms associated. FDC of tadalafil and tamsulosin HCl can be an alternative to co-administration of individual drugs for providing better compliance. Changes in blood pressure should be kept in mind when tadalafil and tamsulosin HCl are co-administered in clinical settings.