Effects of tadalafil once daily on maximum urinary flow rate in men with lower urinary tract symptoms suggestive of benign prostatic hyperplasia

Purpose Tadalafil significantly improves lower urinary tract symptoms suggestive of benign prostatic hyperplasia. We post hoc characterized changes in the maximum urinary flow rate using integrated data from 4 international, placebo controlled studies of tadalafil once daily for lower urinary tract symptoms suggestive of benign prostatic hyperplasia. Materials and Methods After a 4-week placebo lead-in period 1,500 men were randomized to tadalafil 5 mg or placebo for 12 weeks. Data were analyzed using ANCOVA. Maximum urinary flow rate values were rank transformed for analysis. Results Baseline maximum urinary flow rate data were available on 1,371 men with a mean age of 63.1 years and end point data were available on 1,197. Tadalafil 5 mg significantly increased maximum urinary flow vs placebo (median 1.1 vs 0.4 ml per second, p = 0.003). At a baseline voided volume of 125 to less than 250 ml the median change in the maximum urinary flow rate was 0.9 and 1.2 ml per second (p = 0.142) in 731 patients, at a baseline of 250 to 450 ml the change was -0.3 and 0.7 ml per second (p = 0.011) in 428, and at a baseline of greater than 450 ml the change was -0.2 and 2.0 ml per second (p = 0.186) in 38 for placebo and tadalafil, respectively. The difference was 0.3, 1.0 and 2.2 ml per second, respectively. At a baseline maximum urinary flow rate of greater than 15 ml per second in 128 patients the median flow rate change was -2.1 and -0.8 ml per second (p = 0.246), at a maximum of 10 to 15 ml per second in 522 the change was 0.2 and 0.8 ml per second (p = 0.044), and at a maximum of less than 10 ml per second in 547 the change was 1.2 and 1.8 ml per second (p = 0.189) for placebo and tadalafil, respectively. Tadalafil improved I-PSS (International Prostate Symptom Score) voiding subscores significantly vs placebo across all baseline maximum urinary flow subgroups (each p <0.001). Conclusions This integrated analysis revealed a small but statistically significant median maximum urinary flow rate improvement for tadalafil vs placebo. The numerical difference in the maximum urinary flow change from baseline between tadalafil and placebo increased with increased voided volume.