Progesterone is the most important progestogen in the body, the result of its action as a potent agonist of the nuclear progesterone receptor (nPR) (with an affinity of KD = 1 nM) [REF].
Progesterone and some of its metabolites, such as 5β-dihydroprogesterone, are agonists of the pregnane X receptor (PXR),[REF] albeit weakly so (EC50 >10 µM) [REF].