The testosterone patch improves sexual function in postmenopausal women who have hypoactive sexual desire disorder, but the patch's long-term safety needs to be studied, according to a report.
The improvement in frequency of satisfying sexual episodes was “numerically modest,” at 1.4 more such episodes per month, but this amount has been shown to be clinically meaningful in previous studies, said Dr. Susan R. Davis of Monash University, Prahran, Victoria, Australia, and her associates.
This is the first large-scale, phase III clinical trial of testosterone therapy that involved postmenopausal women who were not taking concomitant estrogen.
Testosterone without concomitant estrogen may have adverse effects on the breast and endometrium.
In this study, four cases of breast cancer occurred in women on active treatment, compared with no cases in women taking placebo, and vaginal bleeding also was significantly more common with active treatment.
The study involved women aged 20-70 years who had surgically induced menopause of at least 1 year's duration, and women aged 40-70 years who had natural menopause of at least 2 years' duration. The women all had hypoactive sexual desire and were treated at 65 medical centers in the United States, Canada, Australia, the United Kingdom, and Sweden between 2004 and 2006 (N. Engl. J. Med. 2008;359:2005-17).
The study was sponsored by Procter & Gamble Pharmaceuticals Inc., which also was involved in study design and data collection, and conducted the data analysis. Procter & Gamble makes Intrinsa, a testosterone patch that has been approved by the European Medicines Agency for treatment of hypoactive sexual desire.
A Food and Drug Administration advisory committee recommended against approval of the drug for the U.S. market in 2004.
In the study, 814 women were randomly assigned to use a 150-mcg testosterone patch, a 300-mcg testosterone patch, or a placebo patch every day for 1 year.
The efficacy analysis was performed at 24 weeks, after which the effect of testosterone tends to plateau; the safety analysis was performed at 1 year. A total of 71% of the women completed 24 weeks, and 57% completed the full year.
Compared with the placebo group, both groups on active treatment reported significant increases in sexual desire and frequency of satisfying sexual episodes, as well as decreases in personal distress related to sexual function.
The overall incidence of adverse effects was similar among the three groups.
The most common reasons for withdrawal from the study were patch-site reactions and androgenic events, principally the growth of facial hair.
Dr. Davis reports receiving consulting or lecture fees, and grant support, from Procter & Gamble Pharmaceuticals and other firms.