Overview
C-21 Progestins are a group of Progestins that possess a 21-Carbon Nucleus. C-21 Progestins more closely resemble Natural Progesterone than do 19-Carbon Progestins (which are based on the 19-Carbon Nucleus structure of Nortestosterone) - hence their toxic effects are believed to be somewhat "lesser" than those of C-19 Progestins.
Types ...