Mestranol

Mestranol is the 3-methyl ether of ethinylestradiol. It was the estrogen used in many of the first oral contraceptives.

It is a biologically inactive prodrug of ethinylestradiol to which it is demethylated in the liver with a conversion efficiency of 70% (50 µg of mestranol is  pharmacokinetically bioequivalent to 35 µg of ethinylestradiol).