Placebo Bests Viagra for Treatment
of Sexual Dysfunction in Women

SAN FRANCISCO, May 24 (Reuters Health) - In a multicenter trial of 577 premenopausal and perimenopausal women, sildenafil (Viagra) did not improve sexual response, and at higher doses there was a significant increase in both headaches and flushing.

Placebo was better than sildenafil at every dose studied - 10, 50 and 100 mg, Dr. Rosemary Basson, of the University of British Columbia in Vancouver, said in an interview with Reuters Health. Dr. Basson and colleagues reported their findings in a poster at the 48th annual clinical meeting of the American College of Obstetricians and Gynecologists (ACOG).

Women ages 18 to 55 who had had some type of sexual dysfunction disorder for 6 months or more were enrolled in the study. A 4-week, nontreatment run-in period was followed by a 12-week parallel-group, double-blind period in which subjects were randomized to placebo or one of the three treatment doses.

Thirty-one percent of the 143 women taking 50 mg of sildenafil complained of headache, and 35% of women taking this dose reported flushing, Dr. Basson said. At 100 mg, the standard dose for men, 33% of women had headache and 38% had flushing. "Among men, headache and flushing is about 14% at this dose," she said.

In a prepared statement, Pfizer Pharmaceuticals, manufacturer of Viagra, said that it is proceeding with a phase II trial of sildenafil in postmenopausal women taking hormone replacement therapy. The new trial will enroll 150 women at centers in the United States. The new study will also enroll women who have female sexual arousal disorder as their primary complaint.

Only 48% of the women in the null study presented by Dr. Basson and colleagues at the ACOG meeting had female sexual arousal disorder as their primary complaint. Other diagnoses in the cohort included desire disorder, female orgasmic disorder, hypoactive sexual desire disorder and dyspareunia. The study was conducted at centers in Europe, Australia and Canada.