What does 20-ALPHA-DIHYDROPROGESTERONE stand for? 

20-alpha-dihydroprogesterone

20α-Dihydroprogesterone (20α-DHP), also known as 20α-hydroxyprogesterone (20α-OHP), is a naturally occurring, endogenous progestogen. It is a metabolite of progesterone, formed by the 20α-hydroxysteroid dehydrogenases (20α-HSDs) AKR1C1, AKR1C2, and AKR1C3 and the 17β-hydroxysteroid dehydrogenase (17β-HSD) HSD17B1. 20α-DHP can be transformed back into progesterone by 20α-HSDs and by the 17β-HSD HSD17B2. HSD17B2 is expressed in the human endometrium and cervix among other tissues. In animal studies, 20α-DHP has been found to be selectively taken up into and retained in target tissues such as the uterus, brain, and skeletal muscle.20α-DHP has very low affinity for the progesterone receptor and is much less potent as a progestogen in comparison to progesterone, with about one-fifth of the relative progestogenic activity. It has also been found to act as an aromatase inhibitor and to inhibit the production of estrogen in breast tissue in vitro.A single 200-mg oral dose of micronized progesterone has been found to result in peak levels of 20α-DHP of around 1 ng/mL after 2 hours. In another study however, peak levels of 20α-DHP were around 10 ng/mL during therapy with 300 mg/day oral micronized progesterone. 20α-DHP is formed from progesterone in the liver and in target tissues such as the endometrium. It appears to be more slowly eliminated than progesterone.Levels of 5α-DHP have been quantified.

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