Testosterone for Low Libido in Postmenopausal Women Not Taking Estrogen

Background: The efficacy and safety of testosterone treatment for hypoactive sexual desire disorder in postmenopausal women not receiving estrogen therapy are unknown. Methods: We conducted a double-blind, placebo-controlled, 52-week trial in which 814 women with hypoactive sexual desire disorder were randomly assigned to receive a patch delivering 150 or 300 mu g of testosterone per day or placebo. Efficacy was measured to week 24; safety was evaluated over a period of 52 weeks, with a subgroup of participants followed for an additional year. The primary end point was the change from baseline to week 24 in the 4-week frequency of satisfying sexual episodes. Results: At 24 weeks, the increase in the 4-week frequency of satisfying sexual episodes was significantly greater in the group receiving 300 mu g of testosterone per day than in the placebo group (an increase of 2.1 episodes vs. 0.7, P<0.001) but not in the group receiving 150 mu g per day (1.2 episodes, P=0.11). As compared with placebo, both doses of testosterone were associated with significant increases in desire (300 mu g per day, P<0.001; 150 mu g per day, P=0.04) and decreases in distress (300 mu g per day, P<0.001; 150 mu g per day, P=0.04). The rate of androgenic adverse events - primarily unwanted hair growth - was higher in the group receiving 300 mu g of testosterone per day than in the placebo group (30.0% vs. 23.1%). Breast cancer was diagnosed in four women who received testosterone (as compared with none who received placebo); one of the four received the diagnosis in the first 4 months of the study period, and one, in retrospect, had symptoms before undergoing randomization. Conclusions: In postmenopausal women not receiving estrogen therapy, treatment with a patch delivering 300 mu g of testosterone per day resulted in a modest but meaningful improvement in sexual function. The long-term effects of testosterone, including effects on the breast, remain uncertain. (ClinicalTrials.gov number, NCT00131495.).