title: Effect of chronic sildenafil treatment on penile endothelial function: a randomized, double-blind, placebo controlled study.
abstract: OBJECTIVE
  Although the effect of phosphodiesterase type 5 inhibitors on endothelial function in the systemic circulation has been extensively studied, its effect on penile endothelial function remains unexplored. Therefore, we evaluated the effect of daily sildenafil on penile endothelial function.
  
  
  METHODS
  A total of 60 patients with erectile dysfunction were randomized blindly to daily placebo or 50 mg sildenafil for 4 weeks. Penile and forearm blood flow as well as endothelial function indices were measured at baseline and after 4 weeks using venoocclusive strain gauge plethysmography for both organs. Sequential changes in flow, maximal blood flow and area under the curve induced by reactive hyperemia after 5 minutes of transient ischemia were considered indices of endothelial function.
  
  
  RESULTS
  There were 34 patients treated with sildenafil and 19 on placebo who completed the study. The general characteristics of both groups were comparable. Mean +/- SEM baseline penile blood flow was 6.2 +/- 1.4 and 7.0 +/- 0.6 ml/dl per minute for the placebo and sildenafil groups, respectively (p = 0.54). Baseline forearm blood flow was similar in both groups. At baseline penile AUC was 420 +/- 50 and 520 +/- 50 (p = 0.18), and in the forearm it was 445 +/- 40 and 410 +/- 40 (p = 0.45) for the placebo and sildenafil groups, respectively. After 4 weeks on the assigned drug penile blood flow increased to 11.2 +/- 2 ml/dl per minute in the sildenafil group (p = 0.02) and remained unchanged in the placebo group. After 4 weeks penile AUC increased to 720 +/- 65 in the sildenafil group (0.04) and remained unchanged in the placebo group. Placebo and sildenafil did not affect the indices of forearm endothelial function.
  
  
  CONCLUSIONS
  Daily sildenafil significantly improves penile blood flow and penile endothelial function indices without causing any relevant systemic effects.
authors.affiliation: Neurourology Unit, Rambam Medical Center and Faculty of Medicine, Technion, Israel Institute of Technology, Haifa, Israel. yvardi@rambam.health.gov.il
authors.forename: Yoram
authors.initials: Y
authors.lastname: Vardi
authors.forename: Boaz
authors.initials: B
authors.lastname: Appel
authors.forename: Yaron
authors.initials: Y
authors.lastname: Ofer
authors.forename: Ilan
authors.initials: I
authors.lastname: Greunwald
authors.forename: Lior
authors.initials: L
authors.lastname: Dayan
authors.forename: Giris
authors.initials: G
authors.lastname: Jacob
mesh_terms: D000328:Adult; D000368:Aged; D004311:Double-Blind Method; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology*; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010413:Penis / Q000098:blood supply*; D010726:Phosphodiesterase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D010879:Piperazines / Q000008:administration & dosage / Q000494:pharmacology*; D011687:Purines / Q000008:administration & dosage / Q000494:pharmacology; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate