Darunavir and Efavirenz interaction
Darunavir and Efavirenz: 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 Efavirenz label · effective 2024-03-31
Protease inhibitor: Lopinavir/ritonavir ↓ lopinavir * Lopinavir/ritonavir once daily dosing is not recommended when coadministered with efavirenz.
…Alteration in Dose or Regimen May Be Recommended Based on Drug Interaction Studies or Predicted Interaction Concomitant Drug Class: Drug Name Effect Clinical Comment HIV antiviral agents Protease inhibitor: Fosamprenavir Calcium ↓ amprenavir Fosamprenavir (unboosted): Appropriate doses of the combinations with respect to safety and efficacy have not been established.
Protease inhibitor: Atazanavir ↓ atazanavir * Treatment-naive patients: When coadministered with efavirenz, the recommended dose of atazanavir is 400 mg with ritonavir 100 mg (together once daily with food) and efavirenz 600 mg (once daily on an empty stomach, preferably at bedtime).
Protease inhibitor: Indinavir ↓ indinavir * The optimal dose of indinavir, when given in combination with efavirenz, is not known.
Protease inhibitor: Ritonavir ↑ ritonavir * ↑ efavirenz * Monitor for elevation of liver enzymes and for adverse clinical experiences (e.g., dizziness, nausea, paresthesia) when efavirenz is coadministered with ritonavir.
From the Darunavir (PREZISTA) label · effective 2025-08-29
Initiation of medications that inhibit or induce CYP3A may increase or decrease concentrations of PREZISTA/ritonavir, respectively.
Drugs that induce CYP3A activity would be expected to increase the clearance of darunavir and ritonavir, resulting in lowered plasma concentrations of darunavir and ritonavir.
Co-administration of darunavir and ritonavir and other drugs that inhibit CYP3A, or P-gp may decrease the clearance of darunavir and ritonavir and may result in increased plasma concentrations of darunavir and ritonavir (see Table 10 ).
Corticosteroids: dexamethasone (systemic) ↓ darunavir Co-administration of PREZISTA/ritonavir with systemic dexamethasone or other systemic corticosteroids that induce CYP3A may result in loss of therapeutic effect and development of resistance to darunavir.
…Clinically Significant Interactions with PREZISTA No dosage adjustments are recommended when PREZISTA/ritonavir is co-administered with the following medications: atazanavir, dolutegravir, efavirenz, etravirine, nevirapine, nucleoside reverse transcriptase inhibitors (abacavir, emtricitabine, emtricitabine/tenofovir alafenamide, lamivudine, stavudine, tenofovir disoproxil…
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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.