Testosterone levels in women decline with age, beginning in the late reproductive years. This can lead to a decrease in sexual desire and satisfaction. However, to date, there are few treatment options for this condition. Most studies and treatment options have focused on combining estrogen and testosterone therapy in postmenopausal women, but now, a study in The New England Journal of Medicine reports that testosterone alone may be appropriate therapy for postmenopausal women experiencing low sexual desire.

The researchers conducted a year-long double-blind, placebo-controlled study of more than 800 postmenopausal women with low sexual desire who were not receiving estrogen therapy. The women were randomly assigned to receive a placebo, or a transdermal testosterone patch delivering either 150 micrograms (mcg) or 300 mcg of testosterone per day. The efficacy of the testosterone on libido was evaluated for 24 weeks, while the safety of the testosterone was evaluated for 52 weeks. A small subgroup of women was followed for an additional year to further evaluate the safety of daily testosterone therapy.

The women receiving 300 mcg of testosterone daily received the greatest benefit. The number of satisfying sexual encounters increased significantly to 2.1 episodes per 4-week period, compared to 0.7 episodes in the placebo group. The women receiving 150 mcg of testosterone daily also experienced an increase in sexual encounters (1.2 episodes per 4-week period) compared to the placebo group, but the change was not statistically significant. Both doses of testosterone were associated with significant increases in sexual desire, as well as decreases in distress.

The long-term follow-up period of the study was sufficient to discover some significant adverse effects associated with testosterone treatment. Most significantly was the rate of unwanted hair growth in the women receiving testosterone, with 30% experiencing this effect in the higher-dose group, and 23.1% in the lower-dose group. Also, 4 cases of breast cancer were diagnosed among the study participants receiving testosterone, compared to no new cases in the placebo group. One of these new cases was diagnosed in the first 4 months of the study, and another case had symptoms of breast cancer before the study began.

Another recent study in The Annals of Internal Medicine also studied transdermal testosterone treatment alone for low libido, but evaluated premenopausal women. The 261 women involved in this study applied a testosterone spray to the abdomen daily, and also experienced a significant increase in sexual desire and satisfaction. However, this was a smaller, shorter study, and included women who had low testosterone levels at baseline.

Most studies of low libido in women report success with combination estrogen and testosterone therapy. This new research, however, provides and option for women who cannot or will not be treated with estrogen therapy. It may offer treatment options for younger groups of women experiencing low sexual desire, or offer options for special patient populations, including cancer survivors, or those who have lost ovarian or uterine structures of function due to disease or surgery. More long-term safety studies are needed to fully evaluate the risks associated with long-term testosterone treatment in women, but the results are promising for women with low sexual desire and function.

References

D. L. Barton, D. B. Wender, J. A. Sloan, R. J. Dalton, E. P. Balcueva, P. J. Atherton, A. M. Bernath, W. L. DeKrey, T. Larson, J. D. Bearden, P. C. Carpenter, C. L. Loprinzi (2007). Randomized Controlled Trial to Evaluate Transdermal Testosterone in Female Cancer Survivors With Decreased Libido; North Central Cancer Treatment Group Protocol N02C3 JNCI Journal of the National Cancer Institute, 99 (9), 672-679 DOI: 10.1093/jnci/djk149

S. R. Davis, M. Moreau, R. Kroll, C. Bouchard, N. Panay, M. Gass, G. D. Braunstein, A. L. Hirschberg, C. Rodenberg, S. Pack, H. Koch, A. Moufarege, J. Studd (2008). Testosterone for Low Libido in Postmenopausal Women Not Taking Estrogen New England Journal of Medicine, 359 (19), 2005-2017 DOI: 10.1056/NEJMoa0707302

Davis S, Papalia MA, Norman RJ, et al. Safety and efficacy of a testosterone metered-dose transdermal spray for treating decreased sexual satisfaction in premenopausal women: a randomized trial. Ann Intern Med. Apr 15 2008;148(8):569-577.

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