Methadose 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 methadone may decrease the effects of methadone. 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.

MONITOR: Coadministration with the non-nucleoside reverse transcriptase inhibitors (NNRTIs) efavirenz or nevirapine may decrease the plasma concentrations of methadone. The mechanism is NNRTI induction of methadone metabolism via CYP450 3A4. In 11 patients on stable methadone maintenance therapy, initiation of antiretroviral therapy containing efavirenz (600 mg once a day) resulted in decreases in mean methadone peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of 48% and 57%, respectively, compared to baseline. Nine patients developed symptoms consistent with methadone withdrawal an average of 8 to 10 days after start of efavirenz, which required a 22% mean increase in methadone dosage. In a similar study using nevirapine (200 mg once daily for 2 weeks followed by 200 mg twice daily), the reduction in mean methadone Cmax and AUC was 36% and 52%, respectively, in 8 patients stabilized on methadone treatment. Withdrawal symptoms occurred in six patients 8 to 10 days after start of nevirapine, and methadone dosage was subsequently increased an average of 16%. Dosage increases of up to 100% and eventual discontinuation of NNRTI therapy have been cited in some case reports.

MANAGEMENT: Caution is advised if efavirenz or nevirapine is prescribed to patients treated with methadone. Pharmacologic response to methadone should be closely monitored and the dosage adjusted accordingly, particularly following initiation or discontinuation of NNRTI therapy in patients who are stabilized on their methadone regimen. Following cessation of NNRTI therapy, it takes approximately 2 to 3 weeks for enzyme activity to return to pre-induction levels. Thus, if NNRTI therapy is discontinued due to adverse events or antiretroviral failure, methadone dosage should be gradually reduced over 2 to 3 weeks to pre-NNRTI levels. For patients treated with efavirenz, clinicians must also bear in mind that neurological adverse effects such as dizziness, headache, insomnia, vivid dreams, nightmares, and agitation may occur in up to 25% of patients shortly (within the first several days) after starting efavirenz. These symptoms may be self-limiting and should be clinically differentiated from symptoms of methadone withdrawal so as to avoid unnecessary increases in methadone dosage and the risk of toxicity.

Methadose

Generic Name: methadone

Brand name: Methadose, Dolophine, Methadose Sugar-Free, Diskets

Synonyms: Methadose (Oral Concentrate)

What is Methadose?

Sustiva

Generic Name: efavirenz

Brand name: Sustiva

Synonyms: n.a.

What is Sustiva?