Drug interactions
Losartan + Ritonavir
Severity: Moderate
Losartan and Ritonavir: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Ritonavir is a strong CYP3A4 inhibitor and also affects other enzymes, so its effect on losartan is unpredictable. Losartan is converted to its active metabolite mainly by CYP2C9 and CYP3A4, so the balance of parent drug and active metabolite may change. The clinical impact on blood pressure control is uncertain.
What this interaction means in plain words
Losartan and Ritonavir can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Losartan belongs to Cardiovascular; Ritonavir belongs to Anti Virals.
Why it happens
Ritonavir inhibits CYP3A4 (and may modulate CYP2C9), altering losartan metabolism and formation of its active metabolite E-3174.
What to do
Monitor blood pressure and renal function when starting or stopping ritonavir in a patient on losartan. Adjust the losartan dose according to response.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Losartan
- Aliskiren + Losartan Contraindicated
- Losartan + Sparsentan Contraindicated
- Amifostine + Losartan Major
- Amiloride + Losartan Major
- Amlodipine-benazepril + Losartan Major
- Amlodipine-hydrochlorothiazide-valsartan + Losartan Major
Other interactions of Ritonavir
- Alfuzosin + Ritonavir Contraindicated
- Amiodarone + Ritonavir Contraindicated
- Avanafil + Ritonavir Contraindicated
- Colchicine + Ritonavir Contraindicated
- Dronedarone + Ritonavir Contraindicated
- Eletriptan + Ritonavir Contraindicated
Frequently asked questions
Can I take Losartan with Ritonavir?
MediHelp rates the interaction as moderate. Losartan and Ritonavir can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Ritonavir is a strong CYP3A4 inhibitor and also affects other enzymes, so its effect on losartan is unpredictable. Losartan is converted to its active metabolite mainly by CYP2C9 and CYP3A4, so the balance of parent drug and active metabolite may change. The clinical impact on blood pressure control is uncertain.
How serious is the interaction between Losartan and Ritonavir?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood pressure and renal function when starting or stopping ritonavir in a patient on losartan. Adjust the losartan dose according to response.
What other medicines interact with Losartan?
MediHelp also lists interactions of Losartan with, for example, Aliskiren, Sparsentan, Amifostine. The full list is on the Losartan page.
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