Testosterone in low doses. It is more relevant to consider the impact on female sexual function of low doses of testosterone, which raise the reduced testosterone levels seen in older women to the higher levels seen in reproductive-aged women.
A series of double-blind, multicenter, randomized, placebo-controlled trials in menopausal women with HSDD examined the impact on sexual function of a transdermal testosterone patch (300 μg) that increased blood testosterone levels to the upper limit of normal for young women.14-17 In these studies, compared with placebo, women using testosterone reported significant improvements in sexual desire, arousal, orgasmic response, frequency, and sexually related distress. Findings were consistent in surgically and naturally menopausal women, with and without the use of concurrent estrogen therapy. Improvements were clinically limited, however. On average, testosterone-treated women experienced 1 to 1.5 additional satisfying sexual events in a 4-week period compared with those treated with placebo. The percentage of women reporting a clinically meaningful benefit from treatment was significantly greater in women treated with testosterone (52%) compared with the placebo-treated women (31%).18 An appreciable placebo response was seen, typical of most studies of therapies for sexual dysfunction.
Safety concerns
Potential risks of testosterone treatment include acne, hirsutism, irreversible deepening of the voice, and adverse changes in lipids and liver function (TABLE 2).19 Adverse effects are dose dependent and are unlikely with physiologically dosed testosterone.
A 1-year study of testosterone patches in approximately 800 menopausal women with HSDD (with a subgroup of women followed for an additional year) provides the most comprehensive safety data available.17 Unwanted hair growth occurred more often in women receiving testosterone, without significant differences in blood biochemistry,hematologic parameters, carbohydrate metabolism, or lipids. Breast cancer was diagnosed in more women receiving testosterone than placebo. Although this finding may have been due to chance, the investigators concluded that long-term effects of testosterone treatment remain uncertain.
The FDA reviewed the data from the testosterone patch studies and determined that testosterone patches were effective for the treatment of HSDD in menopausal women, but more information was needed on long-term safety before approval could be granted. Another company then developed a testosterone gel product that produced similar blood levels as the testosterone patch. It was presumed that there would be similar efficacy; the principal goal of these studies was to examine long-term safety, particularly with respect to breast cancer and cardiovascular disease. Unexpectedly, although it raised testosterone blood levels to the upper limit of normal for young women, the testosterone gel product was no more effective than placebo.20 The clinical trial was ended, with safety data never published.
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