Atazanavir and cobicistat and Sustiva

In the database of official manuals used in the service creation an interaction registered by statistical results of studies was found, which can either lead to negative consequences for the patient health or strengthen a mutual positive effect. A doctor should be consulted to address the issue of joint drug administration.

Using efavirenz together with atazanavir may decrease the effects of atazanavir. Contact your doctor if your condition changes. If your doctor does prescribe these medications together, you may need a dose adjustment or special test to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

ADJUST DOSE: Coadministration with efavirenz may significantly decrease the plasma concentrations of atazanavir. Plasma concentrations of cobicistat, a pharmacokinetic enhancer given concomitantly with atazanavir, may also be reduced. Reduced atazanavir plasma levels may lead to diminished virologic response and possible resistance to atazanavir. The mechanism is efavirenz induction of CYP450 3A4, the isoenzyme responsible for the metabolic clearance of atazanavir and cobicistat. In 27 subjects, efavirenz (600 mg once a day for 14 days) decreased the mean steady-state peak plasma concentration (Cmax), systemic exposure (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. Atazanavir boosted with cobicistat appears more sensitive to the effects of CYP450 3A4 induction by efavirenz than atazanavir boosted with ritonavir; however, pharmacokinetic data are not available.

MANAGEMENT: Concomitant use of efavirenz with unboosted atazanavir, atazanavir-ritonavir, or atazanavir-cobicistat is not generally recommended in either treatment-naive or treatment-experienced patients. However if considered necessary in treatment-naive patients, a prescription of atazanavir 400 mg-ritonavir 100 mg or atazanavir 400 mg-cobicistat 150 mg once daily with food, and efavirenz 600 mg administered once daily on an empty stomach at bedtime, may be considered. Some authorities have also recommended atazanavir 400 mg-ritonavir 200 mg and efavirenz 600 mg, all as a single daily dose with food and close clinical monitoring.

Atazanavir and cobicistat

Generic Name: atazanavir / cobicistat

Brand name: Evotaz

Synonyms: Atazanavir and Cobicistat

What is Atazanavir and cobicistat?

Sustiva

Generic Name: efavirenz

Brand name: Sustiva

Synonyms: n.a.

What is Sustiva?