 No other metabolites besides norethisterone are formed from lynestrenol.As such, its pharmacological activity is essentially identical to that of norethisterone.The conversion of lynestrenol into norethisterone is catalyzed by CYP2C9 (28.0%), CYP2C19 (49.8%), and CYP3A4 (20.4%), while other cytochrome P450 enzymes are each responsible for no more than 1.0% of the total conversion.