Ritonavir and Vincristine interaction
Ritonavir and Vincristine: 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 Ritonavir (Norvir) label · effective 2026-07-23
Anticancer Agents: abemaciclib, apalutamide, dasatinib, encorafenib, ibrutinib, ivosidenib, neratinib, nilotinib, venetoclax, vinblastine, vincristine ↑ anticancer agents ↓ ritonavir # Apalutamide is contraindicated due to potential for loss of virologic response and possible resistance to NORVIR or to the class of protease inhibitors [see Contraindications (…
For vincristine and vinblastine, consideration should be given to temporarily withholding the ritonavir containing antiretroviral regimen in patients who develop significant hematologic or gastrointestinal side effects when ritonavir is administered concurrently with vincristine or vinblastine.
From the Vincristine (VinCRIStine Sulfate) label · effective 2026-02-17
Therefore, the concomitant use of strong CYP3A inhibitors with vincristine sulfate should be avoided.
Therefore, the concomitant use of P-gp inhibitors or inducers should be avoided.
Patients should be frequently monitored for adverse reactions with concomitant use of moderate CYP3A inhibitors (e.g., fluconazole) with vincristine sulfate.
Concurrent use of strong CYP3A inducers (e.g., St.
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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.