Crixivan and Efavirenz, emtricitabine, and tenofovir

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 indinavir may decrease the effects of indinavir. 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 decrease the plasma concentrations of indinavir, even when ritonavir is given simultaneously to boost concentrations of indinavir. The mechanism is efavirenz induction of CYP450 3A4, which may override some of the inhibiting effects of ritonavir on the isoenzyme and accelerate the clearance of both indinavir and ritonavir. In 14 healthy male volunteers given indinavir 800 mg and ritonavir 100 mg orally twice a day for 30 days, the addition of efavirenz (600 mg once a day for 14 days) reduced the peak plasma concentration (Cmax), area under the concentration-time curve (AUC) and trough plasma concentration (Cmin) of indinavir by 17%, 25% and 50%, respectively. Ritonavir Cmax, AUC and Cmin decreased by 34%, 36% and 39%, respectively. Pharmacokinetics of efavirenz in the study were comparable to published data. In the absence of ritonavir, efavirenz has been reported to decrease indinavir Cmax and AUC by 16% and 31%, respectively.

MANAGEMENT: The manufacturer recommends that the dosage of indinavir be increased from 800 mg to 1000 mg every 8 hours when coadministered with efavirenz. When ritonavir is also given as a pharmacokinetic booster, limited data suggest it may be possible to overcome the effects of efavirenz by increasing the ritonavir dosage (e.g., 200 mg twice a day).

Crixivan

Generic Name: indinavir

Brand name: Crixivan

Synonyms: n.a.

What is Crixivan?

Efavirenz, emtricitabine, and tenofovir

Generic Name: efavirenz / emtricitabine / tenofovir

Brand name: Atripla

Synonyms: Efavirenz, Emtricitabine, and Tenofovir Disoproxil Fumarate

What is Efavirenz, emtricitabine, and tenofovir?