Effects of sildenafil citrate on ejaculation latency, detumescence time, and refractory period: placebo-controlled,...

To evaluate whether sildenafil citrate (SC) prolongs ejaculation latency and detumescence time and shortens the refractory period in a laboratory setting.

Two successive double-blind, placebo-controlled, crossover laboratory studies were performed with 30 different healthy volunteers in each study (total of 60). In the first study, the subject ingested placebo or SC. Real-time penile tumescence and rigidity monitoring and audiovisual sexual stimulation was performed. When the subject had his best erection, he applied vibratory stimulation until he ejaculated, and then audiovisual sexual stimulation was stopped. Monitoring was continued until he lost rigidity. The test was repeated with the second medication in 7 to 15 days. In the second study, another group of 30 volunteers were tested, as in the first study, and audiovisual sexual stimulation was continued for an additional hour after ejaculation.

In the first study, the time to ejaculation with vibratory stimulation was 2.23 and 3.89 minutes (P = 0.01) and the time to minimal tip rigidity after ejaculation was 1.93 and 3.1 minutes (P <0,001) in the placebo and SC groups, respectively. In the second study, the time to ejaculation with vibratory stimulation was 2.23 and 4.91 minutes (P = 0.006), the time to best tip rigidity after ejaculation was 19.10 and 15.66 minutes (P = 0.242), and the area under the curve of tip rigidity in 3 minutes after ejaculation was 73.61 and 144.05 (P <0.001) in the placebo and SC groups, respectively.

In this laboratory setting, SC seemed to prolong the ejaculation latency time. The detumescence time was also longer, with better quality. However, we did not show that SC shortens the refractory period after ejaculation.