Bioidentical compounded hormones: a pharmacokinetic evaluation in a randomized clinical trial

Objective: Bioidentical compounded hormone therapy is popular among patients, but providers do not have pharmacokinetic information or dosing guidelines for these preparations. Our objective was to compare the pharmacokinetics of the commonly used compounded preparations with conventional hormonal preparations that are considered bioequivalent in practice.

Methods: We conducted a randomized, blinded, four-arm 16-day clinical trial of forty postmenopausal women assigned to one of three doses of a compounded estrogen cream (Bi-est (80:20); 2.0, 2.5, or 3.0 mg)+compounded oral progesterone 100 mg, or to a conventional estradiol patch (Vivelle-Dot™ 0.05 mg)+Prometrium™ 100mg. Serum levels of estrone, estradiol, estriol, and progesterone were obtained at multiple time intervals during the first 24-h, and at steady-state.

Results: Results were analyzable for 37/40 women. Study medications were well tolerated. The AUC at 24h and at steady-state for estrogens remained consistently lower for all doses of Bi-est tested relative to the patch. The difference was statistically significant for Bi-est 2.0mg (AUC-estradiol=181 vs. 956; p<0.001) and 2.5mg (AUC-estradiol=286 vs. 917; p<0.001). Estriol levels remained low in all study arms. Serum progesterone levels were comparable in conventional vs. compounded groups.

Conclusions: This pharmacokinetic trial showed that the currently used doses of compounded hormones yield lower levels of estrogen compared to the standard-dose estradiol patch. To find comparable doses, further studies are needed. This successfully conducted randomized controlled study attests to the feasibility of using a similar design in the setting of a larger clinical trial.