Mifepristone and Ritonavir interaction
Mifepristone and Ritonavir: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Mifepristone label · effective 2025-09-25
CYP3A inducers: Do not use mifepristone with CYP3A inducers ( 7.3 ).
Avoid co-administration of mifepristone and CYP3A inducers such as rifampin, rifabutin, rifapentin, phenobarbital, phenytoin, carbamazepine, and St.
…mifepristone is contraindicated. [See Contraindications (4.3)] 5.6 Use of Strong CYP3A Inhibitors Mifepristone should be used with caution in patients taking ketoconazole and other strong inhibitors of CYP3A, such as itraconazole, nefazodone, ritonavir, nelfinavir, indinavir, atazanavir, amprenavir, fosamprenavir, clarithromycin, conivaptan, lopinavir/ritonavir, posaconazole,…
Ketoconazole and other strong inhibitors of CYP3A, such as itraconazole, nefazodone, ritonavir, nelfinavir, indinavir, atazanavir, amprenavir and fosamprenavir, clarithromycin, conivaptan, lopinavir /ritonavir, posaconazole, saquinavir, telithromycin, or voriconazole may increase exposure to mifepristone.
The dose of mifepristone should be limited to 900 mg, and strong inhibitors of CYP3A should be used only when necessary. [See Dosage and Administration ( 2.4 ), Warnings & Precautions ( 5.6 ), and Clinical Pharmacology ( 12.3 )] 7.3 CYP3A Inducers No medications that induce CYP3A have been studied when co-administered with mifepristone.
From the Ritonavir (Norvir) label · effective 2026-07-23
Oral Contraceptives or Patch Contraceptives: ethinyl estradiol ↓ ethinyl estradiol Alternate methods of contraception should be considered.
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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.