Effect of tadalafil once daily on prostate blood flow and perfusion in men with lower urinary tract symptoms secondary to benign prostatic hyperplasia: a randomized, double-blind, multicenter, placebo-controlled trial

Objective To assess effects of tadalafil vs placebo on prostatic blood flow measured by transrectal ultrasonography in men aged ≥45 years with moderate-to-severe benign prostatic hyperplasia-lower urinary tract symptoms. Methods After screening and washout, patients were randomized to placebo (n = 50) or tadalafil 5 mg (n = 47) once daily for 8 weeks. Transrectal ultrasonography was performed at baseline, 4, and 8 weeks. The primary efficacy measure was the prostate transition zone (TZ) resistive index (RI). Secondary efficacy measures were RI in the peripheral zone and bladder neck, color pixel intensity (CPI), and color pixel density (CPD) in all 3 regions. Outcomes were assessed using mixed-model repeated-measures analyses. Results The overall treatment effect (tadalafil vs placebo) for the change from baseline through week 8 in prostate TZ RI was not statistically significant (least squares mean change: placebo, -0.01; tadalafil, 0.00; P =.118), nor was the change from baseline in prostate TZ CPI (P =.564) or CPD (P =.592). Results were similar for all flow measures in prostate peripheral zone and bladder neck. The adverse event profile was consistent with previous studies with no new safety findings. Conclusion Tadalafil for 8 weeks in men with BPH-LUTS did not result in detectable decreases in arterial RI or increases in CPI or CPD in the prostate or bladder neck. Detection of changes may not be possible because of already low baseline RI, insufficient sensitivity of techniques used, or may have been confounded by methodologic variability across sites. Alternatively, other possible mechanisms not assessed in this study may be more prominently involved