Methadone with Amprenavir Interaction Details
Brand Names Associated with Methadone
- Diskets®
- Dolophine®
- Methadone
- Methadose®
- Methadose® Oral Concentrate
- Westadone®
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Jan 02, 2024
Interaction Effect
Decreased plasma amprenavir and methadone levels
Interaction Summary
Both amprenavir and methadone plasma concentrations may be decreased with concomitant use, possibly due to induction of CYP3A4-mediated methadone metabolism and/or protein-binding displacement. Concomitant use of amprenavir and methadone should be avoided and an alternative antiretroviral drug considered. In a study of 19 opioid-dependent healthy individuals, the addition of amprenavir to the methadone regimen decreased the methadone plasma concentrations. However, this did not result in opioid withdrawal or methadone dosage adjustments. When concomitant use of amprenavir and methadone is required, monitor patients for loss of amprenavir efficacy. Also, methadone dosage may need to be increased .
Severity
Major
Onset
Delayed
Evidence
Established
How To Manage Interaction
Concomitant use of amprenavir and methadone should be avoided. The combination of amprenavir and methadone may lead to decreased plasma levels of one or both drugs. Consider using an alternative to amprenavir. However, if concomitant therapy is required, monitor patients for loss of amprenavir efficacy. Also, an increase in methadone dosage may be necessary.
Mechanism Of Interaction
Induction of CYP3A4-mediated methadone metabolism; protein binding displacement
Literature Reports
A) In a prospective, open-label, pharmacokinetic study involving 19 opioid-dependent, methadone-maintained healthy subjects, methadone, 44 mg to 100 mg daily, was given for more than 30 days. On study day 1, patients were treated with their usual daily methadone dose. On study days 2 through 11, amprenavir 1200 mg twice daily was given in addition to the usual methadone dose. The Cmax, AUC, and Cmin values of the active metabolite, R-methadone, decreased by 25%, 13%, and 21%, respectively. The Cmax, AUC, and Cmin of the inactive metabolite, S-methadone, decreased 48%, 40%, and 52%, respectively. Compared with the amprenavir levels from a historical control group of 38 healthy men, the methadone plus amprenavir group had decreases of 30%, 27%, and 25% in serum amprenavir AUC, Cmax, and Cmin, respectively. The opioid pharmacodynamics effects did not change significantly. Additionally, there were no signs of opioid withdrawal and methadone dose adjustments were not necessary .
Methadone Overview
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Methadone is used to relieve severe pain in people who are expected to need pain medication around the clock for a long time and who cannot be treated with other medications. It also is used to prevent withdrawal symptoms in patients who were addicted to opiate drugs and are enrolled in treatment programs in order to stop taking or continue not taking the drugs. Methadone is in a class of medications called opiate (narcotic) analgesics. Methadone works to treat pain by changing the way the brain and nervous system respond to pain. It works to treat people who were addicted to opiate drugs by producing similar effects and preventing withdrawal symptoms in people who have stopped using these drugs.
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Definitions
Severity Categories
Contraindicated
These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.
Major
This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.
Moderate
This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.
Minor
While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.
Onset
Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.
Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.
Evidence
Level of documentation of the interaction.
Established: The interaction is documented and substantiated in peer-reviewed medical literature.
Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.
How To Manage The Interaction
Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.
It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.
Mechanism Of Interaction
The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.
Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.
Where Does Our Information Come From?
Information for our drug interactions is compiled from several drug compendia, including:
The prescribing information for each drug, as published on DailyMED, is also used.
Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.
The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.