Study Type--Therapy (RCT) Level of Evidence 1b. What's known on the subject? and What does the study add? Several authors have reported their experience with PDE5 inhibitors alone or in combination with selective serotonin re-uptake inhibitors for treating premature ejaculation. However, to our knowledge, this is the first laboratory design study to evaluate the effects of three PDE5 inhibitors throughout the ejaculation process in men with lifelong premature ejaculation. In this laboratory setting study PDE5 inhibitors seem to prolong ELT but the difference from placebo is significant only in vardenafil. The quality of penile rigidity is better with PDE5 inhibitors in the post-ejaculatory period but the difference is significant only in sildenafil and vardenafil.

Objective: • To evaluate the effects of three phosphodiesterase type 5 (PDE5) inhibitors on the ejaculation process in men with lifelong premature ejaculation using a double-blind laboratory setting.

Patients and methods: • Eighty men with lifelong premature ejaculation, 20 in each group, received placebo, vardenafil (10 mg), sildenafil (50 mg) or tadalafil (20 mg) in a double-blind study design. Placebo or PDE5 inhibitor was ingested after at least 2 h fasting and non-smoking. The subjects were placed in a silent room immediately and real-time penile rigidity and tumescence was monitored. • Subjects read some magazines or newspapers without any sexually stimulating material for 1.5 h. At the end of this period audiovisual sexual stimulation began with a video film and after the 8th minute the subject began vibratory stimulation to the frenular area. • At the beginning of ejaculation the patient stopped stimulation. When the patient began and stopped stimulation, the light near the observer turned on and off and the observer calculated the ejaculation period with a chronometer. The elapsed time was the ejaculation latency time (ELT) in seconds. • There was no interaction between subjects and observer during the test. The ELT, and the qualities of base and tip rigidities during ELT and after ejaculation were calculated.

Results: • Median age of patients was 29 (range 22-39) years and median duration of premature ejaculation was 60 (range 7-180) months and there was no significant difference between groups. Median duration of vibratory stimulation (ELT) of subjects who received placebo was 48.5 s: 53.5 s for sildenafil, 70.0 s for tadalafil and 82.5 s for vardenafil. Compared with the placebo group, ELT was significantly longer only in subjects receiving vardenafil (P = 0.019). • In the post-ejaculatory refractory period, times to last recorded base rigidities were significantly longer than placebo in vardenafil and sildenafil groups with better erection quality (P < 0.01 for each).

Conclusions: • The PDE5 inhibitors seem to prolong ELT and the quality of penile rigidity is better with PDE5 inhibitors in post-ejaculatory period. • These findings suggest that PDE5 inhibitors might have some beneficial effects in men with lifelong premature ejaculation.