• benign prostatic hyperplasia;
  • Japanese;
  • lower urinary tract symptoms;
  • phosphodiesterase type 5 inhibitors;
  • tadalafil

Objectives: To examine the efficacy, safety, and dose response of tadalafil once daily in Japanese men with lower urinary tract symptoms suggestive of benign prostatic hyperplasia (BPH-LUTS).

Methods: Men ≥45 years with moderate-to-severe BPH-LUTS were randomized to once-daily placebo (N = 140), tadalafil 2.5 mg (N = 142), or tadalafil 5.0 mg (N = 140), in a 12-week double-blind phase, followed by a 42-week, tadalafil 5.0 mg open-label extension (OLE) phase (N = 394). The primary outcome was total International Prostate Symptom Score (IPSS) change from baseline to last available observation in the double-blind phase.

Results: The least squares (LS) mean difference between placebo and tadalafil in total IPSS change from baseline was −0.7 (P = 0.201) and −1.1 (P = 0.062) for tadalafil 2.5 and 5 mg, respectively (ANCOVA; a dose-dependent improvement in placebo-adjusted total IPSS for tadalafil 5 mg versus 2.5 mg of 57%). Repeated-measures analyses identified a significant total IPSS change for tadalafil 5 mg (LS mean difference between placebo and tadalafil 5 mg: −1.2; P = 0.035), but not tadalafil 2.5 mg, at week 12. Significant improvements for tadalafil 5 mg were demonstrated (ANCOVA) for IPSS obstructive subscore (P = 0.033) and IPSS quality of life index (P = 0.022). Numerical improvements in IPSS scores were maintained over the OLE phase. Tadalafil was well tolerated with no unexpected adverse events.

Conclusion: Tadalafil (5.0 mg) had a favorable benefit-to-risk profile, supporting further investigation of tadalafil (5.0 mg) in Japanese men with BPH-LUTS.