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Drug Interaction Report

3 potential interactions and/or warnings found for the following 2 drugs:

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Interactions between your drugs

Major

methadone somatropin

Applies to: methadone, Nutropin Depot (somatropin)

Consumer information for this interaction is not currently available.

MONITOR CLOSELY: Coadministration with inducers of various CYP450 isoenzymes may decrease the plasma concentrations of methadone, which is metabolized by CYP450 3A4, 2B6, 2C19, 2C9, and 2D6. Reduced analgesic efficacy or withdrawal symptoms may occur in patients maintained on methadone following the addition of an inducer. Conversely, discontinuation of the inducer may increase methadone plasma concentrations and potentiate the risk of overdose and fatal respiratory depression. The interaction has been reported with several moderate and potent inducers including rifampin, phenytoin, phenobarbital, nevirapine, and efavirenz. In one report, evidence of withdrawal was observed in 21 of 30 patients maintained on methadone who received rifampin for tuberculosis, compared to zero out of 26 who received other antituberculous agents. In a study of 11 patients on stable methadone maintenance treatment, mean methadone peak plasma concentration (Cmax) and systemic exposure (AUC) decreased by 48% and 57%, respectively, following initiation of antiretroviral therapy containing efavirenz 600 mg once a day. 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 with nevirapine given at 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 the non-nucleoside reverse-transcriptase inhibitor have also been described in some reports.

MANAGEMENT: Caution is advised if methadone is prescribed with CYP450 2B6, 2C19, 2C9 and/or 3A4 inducers. Pharmacologic response to methadone should be monitored more closely whenever an inducer is added to or withdrawn from therapy, and the dosage adjusted as necessary.

Drug and food interactions

Moderate

methadone food

Applies to: methadone

Grapefruit juice can increase the blood levels and effects of methadone. If you regularly consume grapefruits or grapefruit juice, you should be monitored for side effects and/or changes in methadone levels. Do not increase or decrease the amount of grapefruit products in your diet without first talking to your doctor. Orange juice is not expected to interact.

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Moderate

methadone food

Applies to: methadone

Do not use alcohol or medications that contain alcohol while you are receiving treatment with methadone. This may increase nervous system side effects such as drowsiness, dizziness, lightheadedness, difficulty concentrating, and impairment in thinking and judgment. In severe cases, low blood pressure, respiratory distress, fainting, coma, or even death may occur. With certain long-acting formulations of narcotic pain medication, consumption of alcohol may also cause rapid release of the drug, resulting in high blood levels that may be potentially lethal. Talk to your doctor or pharmacist if you have questions on how to take this or other medications you are prescribed. Do not use more than the recommended dose of methadone, and avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medication affects you. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medication without first talking to your doctor.

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Therapeutic duplication warnings

No duplication warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.


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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.