Estradiol and dienogest and Phentermine and topiramate interaction
Estradiol and dienogest and Phentermine and topiramate: 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 Phentermine and topiramate label · effective 2026-05-18
Oral Contraceptives Clinical Impact Co-administration of multiple-dose phentermine and topiramate extended-release capsules 15 mg/92 mg once daily with a single dose of oral contraceptive containing 35 µg ethinyl estradiol (estrogen component) and 1 mg norethindrone (progestin component), in obese otherwise healthy volunteers, decreased the exposure of ethinyl…
Although this interaction is not anticipated to increase the risk of pregnancy, irregular bleeding (spotting) may occur more frequently due to both the increased exposure to the progestin and lower exposure to the estrogen, which tends to stabilize the endometrium.
Oral Contraceptives : Altered exposure of progestin and estrogen may cause irregular bleeding, but not increased risk of pregnancy.
Intervention Inform patients not to discontinue their combination oral contraceptive if spotting occurs, but to notify their health care provider if the spotting is troubling to them.
Advise patients not to discontinue oral contraceptives if spotting occurs ( 7 ).
From the Estradiol and dienogest (Natazia) label · effective 2024-06-26
Some drugs or herbal products that may decrease the effectiveness of hormonal contraceptives include phenytoin, barbiturates, carbamazepine, bosentan, felbamate, griseofulvin, oxcarbazepine, rifampin, topiramate and products containing St.
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.
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.