Inducers of cytochrome P450 enzymes like CYP3A4 such as St. John's wort, phenobarbital, carbamazepine and rifampicin decrease the circulating levels of<unk> by accelerating its metabolism, whereas inhibitors of cytochrome P450 enzymes like CYP3A4 such as erythromycin, cimetidine, clarithromycin, ketoconazole, itraconazole, ritonavir and grapefruit juice may slow its metabolism resulting in increased levels of<unk> in the circulation. There is an interaction between<unk> and alcohol such that alcohol considerably increases circulating levels of<unk> during oral<unk> therapy and also increases<unk> levels in normal premenopausal women and with parenteral<unk> therapy. This appears to be due to a decrease in hepatic 17β-hydroxysteroid dehydrogenase type 2 (17β-HSD2) activity and hence<unk> inactivation into estrone due to an alcohol-mediated increase in the ratio of NADH to NAD in the liver. Spironolactone may reduce the bioavailability of high doses of oral<unk>
Estradiol 
Estrogen
Estrogen 
Alfatradiol
Androgen
17α-Estradiol
Progesterone 
Progesterone