Estradiol and dienogest and Fosamprenavir interaction
Estradiol and dienogest and Fosamprenavir: 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 Fosamprenavir (Fosamprenavir Calcium) label · effective 2026-06-30
Fosamprenavir calcium: ↓ Amprenavir ↓ Ethinyl estradiol May lead to loss of virologic response. a Fosamprenavir calcium/ritonavir: ↓ Ethinyl estradiol Increased risk of transaminase elevations.
Oral contraceptives: Ethinyl estradiol/norethindrone a Alternative methods of non-hormonal contraception are recommended.
From the Estradiol and dienogest (Natazia) label · effective 2024-06-26
…exposure at steady state. [See Clinical Pharmacology (12.3).] Substances Increasing the Systemic Exposure of COCs (enzyme inhibitors): Concomitant administration of moderate or strong CYP3A4 inhibitors like azole antifungals (for example, ketoconazole, itraconazole, voriconazole, fluconazole), verapamil, macrolides (for example, clarithromycin, erythromycin), diltiazem,…
In a multiple dose study investigating the effect of CYP3A4 inhibitors (ketoconazole and erythromycin) on Natazia, steady state estradiol and dienogest exposures were increased when co-administered with ketoconazole or erythromycin [see Clinical Pharmacology ( 12.3 )] .
Human Immunodeficiency Virus (HIV)/Hepatitis C Virus (HCV) Protease Inhibitors and Non-Nucleoside Reverse Transcriptase Inhibitors : Significant changes (increase and decrease) in plasma concentrations of estrogen and progestin have been noted in some cases of co-administration of HIV/HCV protease inhibitors or with non-nucleoside reverse transcriptase inhibitors.
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.