Drug interactions between Reyataz and Sustiva
Results for the following 2 drugs: |
|
|---|---|
| Reyataz (atazanavir) | |
| Sustiva (efavirenz) | |
Interactions between your selected drugs
efavirenz ⇔ atazanavir
Applies to: Sustiva (efavirenz) and Reyataz (atazanavir)
ADJUST DOSE: Coadministration with efavirenz may significantly decrease the plasma concentrations of atazanavir. The mechanism is efavirenz induction of CYP450 3A4, the isoenzyme responsible for the metabolic clearance of atazanavir. In 27 study subjects, efavirenz (600 mg once a day for 14 days) decreased the mean steady-state peak plasma concentration (Cmax), area under the concentration-time curve (AUC) and trough plasma concentration (Cmin) of atazanavir (400 mg once a day) by 59%, 74% and 93%, respectively, compared to administration of atazanavir alone. When ritonavir 100 mg was added to the regimen and given simultaneously with atazanavir 300 mg once a day in 13 study subjects, daily administration of efavirenz 600 mg two hours later resulted in atazanavir systemic exposure that was similar to that produced by 400 mg of atazanavir alone.
MANAGEMENT: Treatment-naive patients requiring combination therapy with atazanavir and efavirenz should be prescribed atazanavir 300 mg with ritonavir 100 mg and efavirenz 600 mg, all as a single daily dose with food. Atazanavir should not be used with efavirenz without coadministration of ritonavir. Dosing recommendations for efavirenz and atazanavir in treatment-experienced patients have not been established.
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