Efficacy and safety of fixed-dose oral sildenafil in the treatment of erectile dysfunction of various etiologies

Urology. 1999 May;53(5):1011-8. doi: 10.1016/s0090-4295(98)00643-8.


Objectives: To determine the efficacy and safety of fixed-dose oral sildenafil in patients with erectile dysfunction (ED) of various etiologies.

Methods: In a 12-week, double-blind, randomized, placebo-controlled, fixed-dose study, 514 men (mean age 56 years) with ED were randomized to receive 25, 50, or 100 mg of sildenafil or placebo. The primary etiology of ED was determined to be organic in 32% of men, psychogenic in 25%, or mixed in 43%. Sildenafil or placebo was taken in the home setting approximately 1 hour before sexual activity, not more than once daily. Efficacy was determined by responses to question 3 (ability to achieve an erection) and question 4 (ability to maintain an erection) of the 15-item International Index of Erectile Function (IIEF). Other measures of efficacy included the five sexual function domains of the IIEF, a global efficacy question, event log data, and a partner questionnaire.

Results: Sildenafil significantly increased patients' ability to achieve and maintain erections (P <0.0001), with efficacy increasing with increasing dose. Significant improvements were also observed in the IIEF domains for erectile function, orgasmic function, intercourse satisfaction, and overall sexual satisfaction (P <0.0001). The proportion of subjects who felt that treatment with sildenafil improved their erections was significantly greater (67% to 86%) than that with placebo treatment (24%, P <0.0001). The proportion of successful attempts at sexual intercourse also increased significantly with sildenafil treatment (P <0.001). Partner responses corroborated patient reports. Sildenafil was well tolerated at the three doses studied.

Conclusions: Oral sildenafil is an effective, well-tolerated treatment for ED of various etiologies.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Adult
  • Aged
  • Double-Blind Method
  • Erectile Dysfunction / drug therapy*
  • Humans
  • Male
  • Middle Aged
  • Piperazines / administration & dosage*
  • Purines
  • Sildenafil Citrate
  • Sulfones


  • Piperazines
  • Purines
  • Sulfones
  • Sildenafil Citrate