Prezcobix (Darunavir and Cobicistat) + Antibiotics

Coadministration of Prezcobix with antibiotics may give mixed results. It is highly recommended not to co-administer ARV medicines with any antibiotics without the help of a medical specialist. Interactions may occur and can cause serious side effects on your health.

Main Information About Prezcobix

Prezcobix is a highly effective antiretroviral medicine with two active ingredients – cobicistat and darunavir. Darunavir medicine belongs to the protease inhibitors class of drugs while cobicistat is a booster. Its mode of action is to raise and maintain the levels of darunavir in the blood.

Prezcobix is approved as part of a combination therapy for HIV treatment. It’s a continual ART regimen that must be taken continuously together with other antiretrovirals to effectively lower the replication of the virus by inhibiting the virus protease enzyme. Its efficacy suppresses the viral load, boosts the levels of CD4+ cell count and prevents the virus from further destruction of the immune function [1].

How Antibiotics Interact with Prezcobix?

There are various macrolide antibiotics that are highly effective in preventing major bacterial infections, particularly in patients living with HIV. These antibiotics (especially co-trimoxazole or a combination of azithromycin and atovaquone) are extensively used in individuals living with HIV around the world.

However, despite their efficacy in reducing the HIV-related mortality, if used alongside life-prolonging ARV drugs, co-trimoxazole, among other antibiotics, can cause potentially serious negative effects (especially liver injury) and its prolonged administration can lead to bacterial resistance [2].

Although there is a limited clinical study on ARV interactions with antibiotics, the use of rifabutin with Prezcobix may raise rifabutin levels. If this coadministration is needed, it is recommended to use 150 mg of rifabutin once a day or 300 mg three times a week with close monitoring of antimycobacterial activity and considering therapeutic drug adjustments.

The use of rifampin and darunavir is not recommended, and an alternative antibiotic such as rifabutin may be used instead. This combination may lower darunavir levels which decreases darunavir efficacy.

Darunavir with clarithromycin requires monitoring, or preferred alternative such as azithromycin may be used, as their combination may lower darunavir Cmax by 17% and raises clarithromycin AUC levels by 57%. A medical specialist must monitor clarithromycin-related toxicities while reducing clarithromycin dose by 50% for HIV individuals having CrCl 30– 60 mL/min or lower clarithromycin dose by 75% if CrCl is <30 mL/min.

There is no clinical study on cobicistat interaction with antibiotics but co-administering may potentially increase effects on either medicine [3].


  2. Daily co-trimoxazole prophylaxis in severely immunosuppressed HIV-infected adults in Africa started on combination antiretroviral therapy: an observational analysis of the DART cohort. Dr AS Walker, PhD D Ford, PhD Prof CF Gilks, FRCP P Munderi, MBChB F Ssali, MBChB A Reid, MBChB et al. Retrieved March 29, 2010.
  3. Database of Antiretroviral Drug Interactions. Interactions between Antibiotics (including antimycobacterials) and Antiretrovirals.
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