The effects of phosphodiesterase type 5 inhibitors on penile rigidity variables during a period with no sexual stimulation: a laboratory setting double‐blind study
Authors: Gökçe Ahmet , Demirtas Abdullah , Halis Fikret , Ekmekcioglu Oguz 
Published: April 2010

Study Type – Therapy (RCT) Level of Evidence 1b What’s known on the subject? and What does the study add? There is a positive effect of PDE5 inhibitors on several aspects of the men’s sex lives, chiefly erectile function, personal self‐esteem, and satisfaction from their sex lives. To our knowledge, our study is the first study to evaluate the effects of PDE5 inhibitors on erectile variables simultaneously in a laboratory setting. In the present study, significant penile rigidities were obtained with PDE5 inhibitors in a short period, with no sexual stimulation, in laboratory conditions. Our findings might support the use of PDE5 inhibitors in the men who need penile rehabilitation.OBJECTIVETo investigate the effects of phosphodiesterase type 5 (PDE5) inhibitors on erectile variables during a period with no sexual stimulation in a laboratory setting double‐blind study.PATIENTS AND METHODSIn all, 80 men without erectile dysfunction (ED) but with lifelong premature ejaculation (PE) were included in the study. The men were divided equally in to four groups and received either placebo, vardenafil (10 mg), sildenafil (50 mg) or tadalafil (20 mg) in a double‐blind study design. The men attended the laboratory following 3 days of sexual abstinence and placebo or one of the PDE5 inhibitors was ingested after ≥2 h of fasting and non‐smoking. The men were then immediately placed in a silent room and real‐time penile rigidity and tumescence monitoring with Rigiscan Plus (Rigiscan Plus® System, Osbon Medical Systems, Augusta, GA, USA) began. The men read some magazines or newspapers that contained no sexually stimulating material for 1.5 h. There was no interaction between the men and observer during the test period. Times to first measured and total durations of base and tip rigidities, and also total and per minute rigidity were evaluated.RESULTSThe recorded base and/or tip rigidity ratios were 40% (eight of 20), 71% (12/17), 47% (nine of 19) and 70% (14/20) in men who took placebo, sildenafil, tadalafil and vardenafil, respectively (P= 0.126). The ratio of men who could obtain ≥60% base and/or tip rigidities were 10% (two of 20), 41% (seven of 17), 26% (five of 19) and 55% (11/20) in placebo, sildenafil, tadalafil and vardenafil groups, respectively (P < 0.05). The median time to first measured base rigidity was 58.0, 21.5, 54.5 and 57 min with placebo, sildenafil, tadalafil and vardenafil, respectively (P= 0032). The median total duration of recorded base rigidity was 4.0, 27.5, 10.0 and 11.5 min in men who took placebo, sildenafil, tadalafil and vardenafil, respectively (P= 0.013). The median total base rigidity (area under the curve) was 72.8, 699.0, 360.5 and 553.0 with placebo, sildenafil, tadalafil and vardenafil, respectively (P= 0.016).CONCLUSIONSSignificant penile rigidities were obtained with PDE5 inhibitors during the short test period, with no sexual stimulation, in laboratory conditions. This finding might support the use of PDE5 inhibitors in men who need penile rehabilitation.