Estradiol and dienogest and Fosphenytoin interaction
Estradiol and dienogest and Fosphenytoin: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Fosphenytoin (CEREBYX) label · effective 2025-08-28
…omeprazole Sulfonamides Sulfamethizole, sulfaphenazole, sulfadiazine, sulfamethoxazole-trimethoprim Other Acute alcohol intake, amiodarone, chloramphenicol, chlordiazepoxide, disulfiram, estrogen, fluvastatin, isoniazid, methylphenidate, phenothiazines, salicylates, ticlopidine, tolbutamide, trazodone, warfarin Drugs that may decrease phenytoin serum levels Antineoplastic…
Other Corticosteroids, doxycycline, estrogens, furosemide, oral contraceptives, paroxetine, quinidine, rifampin, sertraline, theophylline, and vitamin D Drugs whose level is decreased by phenytoin Anticoagulants Apixaban, dabigatran, edoxaban, rivaroxaban Antiepileptic drugs The effect of phenytoin on phenobarbital, valproic acid and sodium valproate serum levels…
From the Estradiol and dienogest (Natazia) label · effective 2024-06-26
Women who take medications that are strong CYP3A4 inducers should not choose Natazia as their oral contraceptive while using these inducers and for at least 28 days after discontinuation of these inducers due to the possibility of increased breakthrough bleeding and/or decreased contraceptive efficacy.
Multiple dose co-administration of the strong CYP3A4 inducer rifampin with estradiol valerate/dienogest tablets in healthy postmenopausal women led to a decrease in dienogest and estradiol systemic exposure at steady state. [See Clinical Pharmacology (12.3).] Substances Increasing the Systemic Exposure of COCs (enzyme inhibitors): Concomitant administration of…
• CYP3A4 induction : Women taking strong CYP3A4 inducers (for example, carbamazepine, phenytoin, rifampicin, and St.
Drug Interactions Women who take medications that are strong cytochrome P450 3A4 (CYP3A4) inducers (for example, carbamazepine, phenytoin, rifampicin, and St.
Counsel patients to use a back-up or alternative method of contraception when enzyme inducers are used with COCs.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.