Efficacy and safety of simenafil in erectile dysfunction: a phase II, randomized, double-blind, placebo-controlled, crossover study

Simenafil, a newly developed oral phosphodiesterase type 5 (PDE5) inhibitor, substantially improves erectile function; however, its efficacy has not been evaluated via RigiScan monitoring. This study evaluated the efficacy and safety of simenafil in erectile dysfunction (ED) using audiovisual sexual stimulation. A randomized, double-blind, placebo-controlled, multicenter, two-cohort, three-way crossover study was conducted in 84 men aged 18-65 years with mild-to-moderate ED of ≥6 months. Each patient received placebo, simenafil 5.0 mg, and simenafil 2.5 mg (Cohort A, n = 42) or 10.0 mg (Cohort B, n = 42) administered in random order at least 5 days apart. RigiScan was used to assess the time to achieve and duration of ≥60% penile rigidity. In Cohort A, relative to placebo, 2.5 mg simenafil (single-dose) led to a least square mean (LSM) increase in the duration of ≥60% penile rigidity of 3.1 min (95% confidence interval [CI]: 0.5-5.7 min, P = 0.021) and 8.3 min (95% CI: 3.5-13.2 min, P = 0.001) at the tip and base, respectively; for the 5.0 mg, it was 3.7 min (95% CI: 1.0-6.4 min, P = 0.008) and 8.5 min (95% CI: 3.5-13.5 min, P = 0.001) at the tip and base, respectively. In Cohort B, the LSM duration of ≥60% rigidity of the penile base was significantly longer with 10.0 mg simenafil than with placebo by 5.9 min (95% CI: 0.8-10.9 min, P = 0.023). The 5.0 mg (tip and base) and 10.0 mg (tip) simenafil were not statistically significant compared with the placebo (all P > 0.05). The pharmacodynamic and safety profiles support simenafil as a suitable candidate for further investigation in ED.