The androgenicity of progestational agents.

Androgenic potency of the progestational component in oral contraceptives (OCs) is difficult to assess. All the 19-nor testosterone progestogens in OC formulations basically have similar potencies and androgenic activities with the exception of norgestrel (NG). NG is the most potent and androgenic of these agents. It is five to ten times as potent as norethindrone (NET); levonorgestrel (1-NG), one of the two isomers of NG and the one responsible for its potency, is ten to 20 times more potent than NET. In addition, 1-NG is several times more androgenic than NET. However, when evaluating OC androgenic potency the antiandrogenic effect of the progestational agent as well as the effects of the estrogenic component have to be considered. Thus, it is useful to assess parameters that are affected by both OC components, such as changes in lipid levels. It may be concluded that given the potential deleterious metabolic effects produced by androgenic compounds, formulations should be used that have the least impact on these parameters.