title: Oral sildenafil in the treatment of erectile dysfunction. Sildenafil Study Group.
abstract: BACKGROUND
  Sildenafil is a potent inhibitor of cyclic guanosine monophosphate hydrolysis [corrected] in the corpus cavernosum and therefore increases the penile response to sexual stimulation. We evaluated the efficacy and safety of sildenafil, administered as needed in two sequential double-blind studies of men with erectile dysfunction of organic, psychogenic, and mixed causes.
  
  
  METHODS
  In a 24-week dose-response study, 532 men were treated with oral sildenafil (25, 50, or 100 mg) or placebo. In a 12-week, flexible dose-escalation study, 329 different men were treated with sildenafil or placebo, with dose escalation to 100 mg based on efficacy and tolerance. After this dose-escalation study, 225 of the 329 men entered a 32-week, open-label extension study. We assessed efficacy according to the International Index of Erectile Function, a patient log, and a global-efficacy question.
  
  
  RESULTS
  In the dose-response study, increasing doses of sildenafil were associated with improved erectile function (P values for increases in scores for questions about achieving and maintaining erections were <0.001). For the men receiving 100 mg of sildenafil, the mean score for the question about achieving erections was 100 percent higher after treatment than at base line (4.0 vs. 2.0 of a possible score of 5). In the last four weeks of treatment in the dose-escalation study, 69 percent of all attempts at sexual intercourse were successful for the men receiving sildenafil, as compared with 22 percent for those receiving placebo (P<0.001). The mean numbers of successful attempts per month were 5.9 for the men receiving sildenafil and 1.5 for those receiving placebo (P<0.001). Headache, flushing, and dyspepsia were the most common adverse effects in the dose-escalation study, occurring in 6 percent to 18 percent of the men. Ninety-two percent of the men completed the 32-week extension study.
  
  
  CONCLUSIONS
  Oral sildenafil is an effective, well-tolerated treatment for men with erectile dysfunction.
authors.affiliation: Department of Urology, Boston University Medical Center, MA 02118, USA.
authors.forename: I
authors.initials: I
authors.lastname: Goldstein
authors.forename: T F
authors.initials: TF
authors.lastname: Lue
authors.forename: H
authors.initials: H
authors.lastname: Padma-Nathan
authors.forename: R C
authors.initials: RC
authors.lastname: Rosen
authors.forename: W D
authors.initials: WD
authors.lastname: Steers
authors.forename: P A
authors.initials: PA
authors.lastname: Wicker
mesh_terms: D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003075:Coitus; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010726:Phosphodiesterase Inhibitors / Q000009:adverse effects / Q000627:therapeutic use*; D010879:Piperazines / Q000009:adverse effects / Q000627:therapeutic use*; D011687:Purines; D000068677:Sildenafil Citrate; D013450:Sulfones; D016896:Treatment Outcome
chemical_list: D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate; D015106:3',5'-Cyclic-GMP Phosphodiesterases