Sex differences in the pharmacokinetics of dehydroepiandrosterone (DHEA) after single- and multiple-dose administration in healthy older adults

The pharmacokinetics of exogenously administered DHEA have not been well ch aracterized despite its increasing use in therapeutic and research investig ations. The purpose of this stud was to evaluate the pharmacokinetics of DH EA and its sulfated metabolite (DHEA-S) after single- and multiple-dose ora l administration of DHEA 200 mg. Healthy older adult volunteers (7 women, 6 men) ages 65 to 79 years were studied on five visits separated by 1 week S ubjects received daily administration of placebo (days 1 to 7), DHEA 200 mg (days 8 to 22), and placebo (days 23 to 29). Blood samples were collected over 24 hours on days 1, 8, 15, 22, and 29 for DHEA and DHEA-S determinatio ns by RIA. Pharmacokinetic parameter estimates were calculated by noncompar tmental methods. Administration of DHEA 200 mg resulted in higher DHEA C-ma x, AUG, and overall concentrations in women than in men (p < 0.03); DHEA-S parameter estimates were similar between men and women. Following a single dose of DHEA 200 mg, DHEA concentrations increased 5- to 6-fold in both men and women, and DHEA-S concentrations increased 5-fold in men and 21-fold i n women relative to endogenous concentrations. The results of this study in dicate th at the pharmacokinetics of DHEA differ between older men and wome n.