Over-the-counter progesterone cream produces significant drug exposure compared to a food and drug administration-approved oral progesterone product.

Authors: Hermann AC, Nafziger AN, Victory J, Kulawy R, Rocci ML Jr, Bertino JS Jr.

Publication Year: 2005

Citation: J Clin Pharmacol 2005; 5(6):614-9.

In 12 healthy, postmenopausal women, steady state levels of progesterone in the blood were measured in a randomized crossover study comparing topical progesterone cream (Pro-gest®, 40 mg twice daily x 12 days ) with oral micronized progesterone (Prometrium®, 200 mg daily x 12 days). There was no significant difference noted in mean steady state levels between the two products as measured by area under the curve (AUC) of progesterone levels in whole blood.  This indicates that equivalent blood levels of progesterone can be achieved with substantially lower doses of topical progesterone cream than with oral micronized progesterone.

http://www.ncbi.nlm.nih.gov/pubmed/15901742