Date of report 23 Dec 2020
Reported case interaction between
Cobicistat and Rifabutin
Cobicistat and Rifabutin
Drugs suspected to be involved in the DDI-summary
Complete list of drugs taken by the patient
rifabutin
Clinical case description
A 63-year-old HIV-infected female with a history of latent TB, cirrhosis secodary to non-alcoholic steatohepatitis. The patient has been treated with rifabutin 300 mg daily for a 4 month treatment course 9 months prior. Due to a communication error, the patient was restarted on rifabutin 300 mg daily for 3 months while on treatment with elvitegravir/cobicistat, emtricitabine and tenofovir alafenamide. The patient developed a bilateral panuveitis likely due to the inhibitory effect of cobicistat on rifabutin metabolism leading to high concentrations of rifabutin. Rifabutin-associated uveitis has been recognized as a dosage-dependent side effect. This report was published by Toomey C et al. Case rep Ophthalmol 2020.
Clinical Outcome
Drug Interaction Probability Scale (DIPS)
Editorial Comment
Coadministration is not recommended as it may significantly decrease elvitegravir/cobicistat plasma concentrations, which may result in loss of therapeutic effect and development of resistance. Coadministration of elvitegravir/cobicistat (150 mg/150 mg once daily) and rifabutin (300 mg once daily alone or 150 mg every other day with elvitegravir/cobicistat) decreased elvitegravir Cmin by 67%. Rifabutin exposure was similar to values obtained alone, but 25-O-desacetylrifabutin exposures were 4.8 to 6.3 fold higher. The European SPC suggests that if the combination is needed, to use rifabutin 150 mg 3 times per week on set days (e.g. Monday-Wednesday-Friday) with increased monitoring for rifabutin associated adverse reactions including neutropenia and uveitis due to increased desacetyl rifabutin exposure
University of Liverpool Recommendation
Potential interaction - may require close monitoring, alteration of drug dosage or timing of administration