Objective: To determine, by post hoc analysis, the effects of tadalafil (a long-acting phosphodiesterase 5 inhibitor) on peak urinary flow (Q(max)), bladder capacity, voiding efficiency and the obstructive symptoms of benign prostatic hyperplasia (BPH) in men with lower urinary tract symptoms secondary to BPH (BPH-LUTS), compared with placebo.
Patients and methods: After a 4-week placebo run-in period, 1058 men with BPH-LUTS were randomly allocated to receive once daily treatment with placebo or tadalafil (2.5, 5, 10, or 20 mg) for 12 weeks. Uroflowmetry, postvoid residual volume (PVR), and BPH symptom score measurements were assessed throughout the trial.
Results: Increases in Q(max) were numerically greater for tadalafil (2.5, 5, 10, and 20 mg with percentage changes of 15%, 16%, 17%, 22%, respectively) vs placebo (12%), but did not reach statistical significance. Age, baseline Q(max), erectile dysfunction history, sexual activity, and previous alpha-blocker therapy significantly influenced the Q(max) response. Tadalafil was not associated with significant changes in PVR. Tadalafil had its greatest effects on bladder capacity and voiding efficiency in men with a Q(max) of <10 mL/s at baseline, but these changes were not significantly different from placebo responses. Tadalafil treatment significantly improved the IPSS obstructive subscores (tadalafil 2.5, 5, 10, 20 mg with percentage changes of 24%, 31%, 33%, 33%, respectively) vs placebo (13%).
Conclusions: Once daily tadalafil did not significantly change Q(max) or voiding efficiency compared with placebo in men with BPH-LUTS, although there were dose-dependent improvements. No subgroups were identified where tadalafil or placebo treatment had a deleterious effect on Q(max). Despite these minimal changes in uroflowmetric measures, tadalafil was associated with clinically meaningful and statistically significant improvements in the obstructive symptoms of BPH.