Does Rifampin Interact With Simvastatin?

This is generally a minor interaction, but review it with your pharmacist to be sure it is safe for you.

Interactions like this one can happen when two medicines have overlapping effects, or when one changes how the other is absorbed, broken down, or cleared from the body. Rifampin is a rifamycin antibiotic (strong cyp3a4 inducer) and Simvastatin is a hmg-coa reductase inhibitor (statin); together they are documented as a minor interaction. How much this matters depends on your dose, your other medications, and your overall health.

If you have been prescribed both Rifampin and Simvastatin, do not start, stop, or change either medication on your own — some medicines are unsafe to stop suddenly. Tell your prescriber and pharmacist that you take both so they can decide whether the combination is right for you, adjust the dose, monitor you more closely, or suggest an alternative.

Decrease exposure Selective 5-HT3 Receptor Antagonists Ondansetron Decrease exposure Statins Metabolized by CYP3A4 Simvastatin Decrease exposure Thiazolidinediones Rosiglitazone Decrease AUC by 66% Tricyclic Antidepressants Nortriptyline A tuberculosis treatment regimen including rifampin (600 mg/day), isoniazid (300 mg/day), pyrazinamide (500 mg 3× per day), and pyridoxine (25 mg) was associated with higher than expected doses of nortriptyline were required to obtain a therapeutic drug level.

Source: FDA structured product labeling (set_id 036ab68e-5085-4edc-bd83-784b43d64eab).