title: Randomized, double-blind, crossover trial of sildenafil in men with mild to moderate erectile dysfunction: efficacy at 8 and 12 hours postdose.
abstract: OBJECTIVE
  To clarify the period of responsiveness to sildenafil.
  
  
  METHODS
  Under a double-blind protocol, men with mild to moderate erectile dysfunction (International Index of Erectile Function [IIEF] Erectile Function domain score, 11 to 25) were randomized to sildenafil (100 mg) or placebo and attempted intercourse 8 hours (range, 7 to 9 hours) postdose (first 4-week phase) and 12 hours (11 to 13 hours) postdose (second 4-week phase after treatment crossover). The primary outcome was the per-patient proportion (PPP; least squares means [95% confidence interval]) of affirmative responses to the Sexual Encounter Profile question 3 (SEP3: "Did your erection last long enough for you to have successful intercourse?").
  
  
  RESULTS
  For sildenafil (n = 174) versus placebo (n = 177), baseline values were similar but the PPP of successful intercourse attempts increased to 76% (69% to 82%) versus 50% (43% to 57%) in phase 1 (odds ratio [OR] = 3.2) and 79% (72% to 85%) versus 52% (44% to 60%) in phase 2 (OR = 3.5), and the PPP of Erection Hardness Score 4 erections (completely hard and fully rigid) was 41% (34% to 48%) versus 10% (7% to 15%) in phase 1 (OR = 6.2) and 44% (37% to 51%) versus 17% (12% to 23%) in phase 2 (OR = 4.0). Thus, at 12 hours, the odds of successful intercourse tripled and of a completely hard erection quadrupled. The sildenafil group achieved greater (P <0.001) PPP of successful penetration (SEP2), satisfaction with erection hardness (SEP4), and satisfaction with the sexual experience (SEP5); improvement in IIEF domain scores; and treatment satisfaction on the Erectile Dysfunction Inventory of Treatment Satisfaction.
  
  
  CONCLUSIONS
  In men with mild to moderate ED, responsiveness to sildenafil may persist much longer than 4 hours.
authors.affiliation: New York University School of Medicine, New York, New York 10016, USA. andy.mccullough@nyumc.org
authors.forename: Andrew R
authors.initials: AR
authors.lastname: McCullough
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Steidle
authors.forename: Brian
authors.initials: B
authors.lastname: Klee
authors.forename: Li-Jung
authors.initials: LJ
authors.lastname: Tseng
mesh_terms: D000328:Adult; D000368:Aged; D018592:Cross-Over Studies; D004311:Double-Blind Method; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006207:Half-Life; D006801:Humans; D008297:Male; D008875:Middle Aged; D009948:Orgasm; D017060:Patient Satisfaction; D010879:Piperazines / Q000493:pharmacokinetics / Q000627:therapeutic use*; D011687:Purines / Q000493:pharmacokinetics / Q000627:therapeutic use; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000493:pharmacokinetics / Q000627:therapeutic use*; D016896:Treatment Outcome; D014665:Vasodilator Agents / Q000493:pharmacokinetics / Q000627:therapeutic use*
chemical_list: D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014665:Vasodilator Agents; D000068677:Sildenafil Citrate