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New research from Australia has found that only small doses of testosterone are needed to raise testosterone back to premenopause levels in postmenopausal women.
Results of a small pharmacokinetics study showed that a 5-mg dose of testosterone, the lowest available dose of testosterone supplementation, was sufficient to raise testosterone back to a premenopause level in postmenopausal women.
The study, published in Menopause, examined a 1% transdermal testosterone supplementation cream (TTC; AndroFeme) that is currently approved in Western Australia.
“In the United States, we do not yet have an approved testosterone product designed for women,” North American Menopause Society Executive Director Margery Gass, MD, said in a prepared statement. “As a result, American women sometimes rely on custom-compounded testosterone prescriptions that may deliver much higher doses than the Australian product and raise women’s testosterone to levels higher than normal, potentially producing untoward side effects.”
Researchers conducted the study in an attempt to further evaluate the pharmacokinetics of the two available treatment doses, 5 mg and 10 mg. The study included seven healthy naturally postmenopausal women aged between 60 and 65 years who were randomly assigned to either 5 mg or 10 mg of the testosterone cream, which was applied daily to their upper arm. The researchers measured serum total testosterone, free testosterone, sex hormone-binding globulin, and metabolite concentrations.
At day 22, women assigned the 5-mg dose had a median peak level of total testosterone of 0.75 ng/mL and median peak free testosterone of 4.70 pg/mL. Patients on the 10-mg dose had a median peak total testosterone of 1.54 ng/mL and a median peak free testosterone of 12.6 pg/mL.
The uncorrected total testosterone was 0.54 ng/mL for the 5-mg dose and 0.91 ng/mL for the 10-mg dose. The uncorrected free testosterone was 4.14 pg/mL for the 5-mg dose and 7.24 pg/mL for the 10-mg dose.
The researchers looked at the mean baseline-corrected concentrations for the 5-mg and 10-mg doses and found that a doubling of the dose only resulted in a 30% increase in total testosterone (0.52 vs 0.69 ng/mL for 5 mg and 10 mg, respectively) and a 31% increase in free testosterone (0.52 vs 0.69 ng/mL for 5 mg and 10 mg, respectively).
“Doubling of the study dose to 10 mg/day resulted in a median total testosterone Cavg [mean serum concentration during the dosing interval] that was almost double the upper limit of reference levels in premenopausal women and in a median free testosterone Cavg that was slightly above the upper limit of the reported premenopausal reference range,” the researchers wrote. “These data suggest that daily application of 5 mg of TTC is likely to restore free testosterone levels to the premenopausal reference range but that higher doses will result in supraphysiological total testosterone and free testosterone levels.”