The effects of phosphodiesterase type 5 inhibitors on penile rigidity variables during a period with no sexual stimulation: a laboratory setting double-blind study.
OBJECTIVE
To 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.


METHODS
In 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.


RESULTS
The 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).


CONCLUSIONS
Significant 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.
Gökçe
Ahmet
A
Department of Urology, Erciyes University Medical Faculty, Kayseri, Turkey. aagokce@yahoo.com
Demirtas
Abdullah
A
Halis
Fikret
F
Ekmekcioglu
Oguz
O
D000293:Adolescent; D000328:Adult; D002243:Carbolines / Q000008:administration & dosage; D004311:Double-Blind Method; D004542:Ejaculation; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D007093:Imidazoles / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D010410:Penile Erection / Q000187:drug effects* / Q000502:physiology; D058986:Phosphodiesterase 5 Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use*; D010775:Photic Stimulation; D010879:Piperazines / Q000008:administration & dosage; D011687:Purines / Q000008:administration & dosage; D011788:Quality of Life; D012725:Sexual Behavior / Q000187:drug effects*; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000008:administration & dosage; D000068581:Tadalafil; D013997:Time Factors; D014227:Triazines / Q000008:administration & dosage; D000069058:Vardenafil Dihydrochloride; D055815:Young Adult
D002243:Carbolines; D007093:Imidazoles; D058986:Phosphodiesterase 5 Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014227:Triazines; D000069058:Vardenafil Dihydrochloride; D000068581:Tadalafil; D000068677:Sildenafil Citrate