Methadone with Chlorpheniramine Interaction Details

Brand Names Associated with Methadone

Brand Names Associated with Chlorpheniramine

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Jan 02, 2024

Interaction Effect

Increased risk of paralytic ileus; increased risk of serotonin syndrome

Interaction Summary

Concomitant use of methadone and serotonergic drugs has resulted in serotonin syndrome and may occur with recommended dosages. The onset of symptoms may occur within several hours to a few days of concomitant use. Additionally, the concomitant use of methadone with anticholinergic drugs may increase the risk of urinary retention and severe constipation, which may lead to paralytic ileus. If concomitant use is needed, carefully observe the patient, particularly during treatment initiation and dose adjustments for serotonin syndrome and observe for signs and symptoms of urinary retention or reduced gastric motility. Discontinue methadone if serotonin syndrome is suspected.

Severity

Major

Onset

Rapid

Evidence

Theoretical

How To Manage Interaction

Concomitant use of methadone and serotonergic drugs has resulted in serotonin syndrome and may occur with recommended dosages. The onset of symptoms may occur within several hours to a few days of concomitant use. Additionally, the concomitant use of methadone with anticholinergic drugs may increase the risk of urinary retention and severe constipation, which may lead to paralytic ileus. If concomitant use is needed, carefully observe the patient, particularly during treatment initiation and dose adjustments for serotonin syndrome and observe for signs and symptoms of urinary retention or reduced gastric motility. Discontinue methadone if serotonin syndrome is suspected.

Mechanism Of Interaction

Additive effects on gastric motility; additive serotonergic effects

Methadone Overview

• 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.

Chlorpheniramine Overview

• Chlorpheniramine relieves red, itchy, watery eyes; sneezing; itchy nose or throat; and runny nose caused by allergies, hay fever, and the common cold. Chlorpheniramine helps control the symptoms of cold or allergies but will not treat the cause of the symptoms or speed recovery. Chlorpheniramine is in a class of medications called antihistamines. It works by blocking the action of histamine, a substance in the body that causes allergic symptoms.

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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:

• Gold Standard Drug Database
• Micromedex
• Lexicomp
• DrugBank

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.