The physiological action of progesterone and the pharmacological effects of progestogens--a short review.

Substances described as progestogens differ greatly in their additional properties, which determine the limitations of their clinical use. The extrapolation of animal assays to human use requires caution, since synergism with oestrogens, which is usually necessary, shows widely-differing species-specific ratios. In other ratios, progestogens are often antagonistic to oestrogens.