Carbamazepine Extended-Release Capsules (Carbatrol) and Sustiva (Efavirenz Capsules)

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 carBAMazepine together with efavirenz may reduce the blood levels and effects of both medications. Your doctor may be able to prescribe alternatives that do not interact, or you may need a dose adjustment or more frequent monitoring by your doctor to safely use both medications. Let your doctor know if your conditions worsen during treatment with these 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.

GENERALLY AVOID: The plasma concentrations of both carbamazepine and efavirenz may decrease during concomitant administration, since both drugs are substrates as well as inducers of CYP450 3A4. In a 2-period crossover pharmacokinetic study, 12 healthy volunteers were randomized to receive either efavirenz 600 mg once daily for 14 days or carbamazepine titrated to 400 mg once daily for 21 days, followed with both drugs for another 21 or 14 days. During coadministration, carbamazepine peak plasma concentration (Cmax), systemic exposure (AUC) and trough plasma concentration (Cmin) decreased by an average of 20%, 27% and 35%, respectively, while efavirenz Cmax, AUC and Cmin decreased by an average of 21%, 36% and 47%, respectively. The pharmacokinetics of the major metabolite of carbamazepine, carbamazepine-10,11-epoxide, were not significantly affected. Convulsions have been observed during efavirenz therapy, generally in patients with a known medical history of seizures. This may be at least partially related to the drug interaction between efavirenz and anticonvulsants including carbamazepine that are primarily metabolized by hepatic CYP450 microsomal isoenzymes.

MANAGEMENT: There are insufficient data to make a dosage recommendation for efavirenz during coadministration with carbamazepine. Given the risk of reduced viral susceptibility and resistance development associated with subtherapeutic antiretroviral drug levels, alternative anticonvulsant treatment should be used if efavirenz is required. Otherwise, pharmacologic effects and serum levels of both drugs should be closely monitored during concomitant use.

Carbamazepine Extended-Release Capsules (Carbatrol)

Generic Name: carbamazepine

Brand name: Carbatrol, Epitol, Equetro, Tegretol, Tegretol XR, Tegretol, Tegretol XR

Synonyms: Carbamazepine, CarBAMazepine

What is Carbamazepine Extended-Release Capsules (Carbatrol)?

Sustiva (Efavirenz Capsules)

Generic Name: efavirenz

Brand name: Sustiva

Synonyms: Sustiva

What is Sustiva (Efavirenz Capsules)?