Dr. Weeks’ Comment: Transdermal progesterone is so effective, regulators want to remove it from OTC status…
J Clin Pharmacol. 2005 Jun;45(6):614-9.
Over-the-counter progesterone cream produces significant drug exposure compared to a food and drug administration-approved oral progesterone product.
Progesterone products are available in prescription form as well as over-the-counter (OTC) topical preparations sold for “cosmetic” uses. In a randomized study design, the authors compared the drug exposure from an OTC progesterone cream to a Food and Drug Administration-approved oral preparation at the labeled daily doses recommended for each product. Twelve healthy postmenopausal women received 200-mg oral progesterone capsules once daily for 12 days or progesterone cream 40 mg twice daily for 12 days. At steady state (day 12 of each phase), whole-blood samples were collected over 24 hours (oral progesterone) or 12 hours (topical progesterone) and assayed for total progesterone concentration. No significant differences were found in dose-normalized 24-hour progesterone exposure comparing the cream to oral capsules (median AUC (0-24) 12.5 ng x h/mL vs 10.5 ng x h/mL, respectively; P = .81). In light of the potential risks associated with long-term progesterone use, the authors question whether topical progesterone products should be available OTC.