Cladribine and Ritonavir interaction
Cladribine 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 Cladribine (Mavenclad) label · effective 2026-05-27
Prevention or Management Avoid co-administration of potent ENT1, CNT3, or BCRP transporter inhibitors (e.g., ritonavir, eltrombopag, curcumin, cyclosporine, dilazep, nifedipine, nimodipine, cilostazol, sulindac, dipyridamole, or reserpine) during the 4 to 5 day MAVENCLAD treatment cycles.
Antiviral and antiretroviral drugs: Avoid concomitant use.
Antiviral and Antiretroviral Drugs Clinical Impact Compounds that require intracellular phosphorylation to become active (e.g., lamivudine, zalcitabine, ribavirin, stavudine, and zidovudine) could interfere with the intracellular phosphorylation and activity of cladribine.
From the Ritonavir (Norvir) label · effective 2026-07-23
Immunosuppressants: cyclosporine, tacrolimus, sirolimus (rapamycin) ↑ immunosuppressants Therapeutic concentration monitoring is recommended for immunosuppressant agents when co-administered with ritonavir.
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.