Strategies to Reduce Methadone-Related Medication Events

Methadone is an effective opioid agonist therapy (OAT) used to manage opioid use disorder. Data from the AIMS Program indicate that methadone is one of the top drugs involved in medication incidents and good catches. It is also the most frequently reported drug involved in severe harm or death.

Methadone is a synthetic oral full-mu opioid agonist. Its slow onset and long duration of action make it an effective treatment for opioid use disorder. However, its unique pharmacological properties can also contribute to a higher risk of medication errors.

Repeated doses of methadone lead to a gradual accumulation in the serum, which can result in a delayed presentation of effects. For example, a dose that initially seems appropriate can lead to fatal overdose after a few days due to respiratory depression. As a result, methadone requires highly individualized dosing to optimize both therapeutic outcomes and patient safety. While the risk of overdose is greatest during initiation/titration, it can also occur during the maintenance phase because of medication errors or the concomitant use of central nervous system depressants.

Pharmacists must exercise heightened caution when dispensing methadone, given its unique pharmacological properties and the severe consequences associated with inappropriate dosing. Incorrect quantity/strength/concentration could result in a too-high dose (risk of overdose) or too-low dose (risk of withdrawal).

Because methadone-related errors are associated with greater harm and risk to patients, implementing strategies to prevent them is essential to improving patient safety.

Recommendations to Minimize Errors

1. Don’t assume a patient’s dose. Confirm the dose with the prescriber and patient.

Methadone has a wide range of therapeutically acceptable doses. There can be several reasons for dose changes – a titration/tapering schedule, to avoid drug–drug interactions, etc. If the pharmacist is unsure about the therapeutic appropriateness of a dose or dose change, they should confirm this with the prescriber and the patient. Given the risk of methadone toxicity, it is also best practice to check the last dose received by the patient.

2. Ensure accurate order entry and inactivate previous prescriptions.

When receiving new prescriptions, enter the complete dosing regimen rather than entering future doses later. Inactivate previous prescriptions and avoid using a “copy” function, as each prescription may involve changes to one or more fields, such as start and stop dates.

3. Complete independent double-checks to verify dose calculations and measurements.

Misinterpretations (e.g., prescriptions communicated in millilitres [mL] rather than milligrams [mg] or missed decimal points) can lead to dosing errors. Integrate independent double-checks within the workflow to ensure correct order entry, dose calculations and dose measurements.

4. Prepare methadone doses in a designated workspace to minimize distractions

Focus on one prescription at a time and follow through to completion. If distracted or interrupted, consider restarting the dose-preparation process.

5. Confirm the patient’s identity and the expected dose.

Use multiple patient identifiers (e.g., name, date of birth, address) to verify the patient’s identity, then have the patient independently confirm their dose. To reduce risk of confirmation basis, use open-ended questions, such as “When is your birthday?” and “What dose are you taking?”

6. Assess the patient and monitor their clinical stability.

Make objective observations and use clinical judgment when a patient arrives for their methadone dose. Pharmacists must ensure the patient is not showing signs of intoxication before witnessing the administration and ingestion of their methadone dose. If a patient is showing signs of toxicity – or withdrawal – this might suggest that they received an incorrect or inappropriate dose of methadone. The pharmacist should investigate further, gather relevant information from the patient and, if necessary, collaborate with the prescriber to determine an appropriate course of action.

Continuous Learning and Improvement

If a medication incident or good catch occurs with methadone (or any medication), report the event in the AIMS Pharmapod platform. Ensure you identify the root cause and implement effective strategies to manage and prevent future events. Share findings and insights with your pharmacy team to improve patient safety.

Important Note on AIMS Data
Data gathered through the AIMS Program is self-reported by community pharmacies through a third-party medication incident reporting platform. The data is not verified by the College; rather, aggregate, de-identified data from the program is shared so that pharmacy professionals can learn from their peers and identify continuous quality improvement opportunities in their own pharmacies. Knowing which types of medication incidents are most likely to occur, when, and why will help pharmacy professionals identify and close gaps and improve patient safety.

References

1. Opioid Use Treatment: Methadone. Centre for Addiction and Mental Health. https://www.camh.ca/en/professionals/treating-conditions-and-disorders/opioid-use/opioid-use-treatment/methadone
2. Oral Opioid Agonist Therapy: A Multi-Incident Analysis of Reports from Community Pharmacies. ISMP Can Saf Bull. November 2023. https://ismpcanada.ca/wp-content/uploads/ISMPCSB2023-i11-Opioid-Agonist-Therapy.pdf
3. SMART Medication Safety Agenda: Methadone. February 2020. https://saskpharm.ca/document/5771/SMART-Methadone-Feb2020.pdf
4. College of Pharmacists of Manitoba. Methadone Maintenance Treatment: Quick Guide to Keep Your Patients, Staff, and Community Safe. https://cphm.ca/wp-content/uploads/Resource-Library/Opioid-Agonist-Therapy/MMT-Safety-Quick-Guide.pdf