Methadone Safety Issues | Contraindications | Mechanism of Action

Methadone Safety Issues | Contraindications | Mechanism of Action

Safety issues

Methadone is always confused with sound or look alike drugs such as dexmethylphenidate or methylphenidate.

Methadone has been listed in the drug classes under the Institute for Safe Medication Practices (ISMP) which may post heightened risk or harm to patient when used in error.

Contraindications

Respiratory depression in which in the absence of resuscitative equipment or in an unmonitored condition, acute bronchial asthma or hypercarbia, paralytic ileus, concurrent use of selegiline

Precautions

As with other opioid-containing analgesic regimen, methadone should be tailored to each patient's needs and based on the type of pain being managed, such as the factors of acute versus chronic, route of administration, degree of tolerance for opioids, age, weight, and other medical conditions. Also, the optimal analgesic dose varies widely among different individuals and methadone doses should be titrated to pain relief. Patients on stable maintenance doses of methadone may require higher doses in case of acute pain, for example during postoperative pain and physical trauma. It is noted that methadone is ineffective for anxiety relief.

Methadone may prolong the QT interval and increase risk of torsade de pointes. Before starting methadone treatment, patients should be informed of the potential arrhythmia risk, and assessed for history of structural heart disease, arrhythmia, syncope, or any potential drug interactions including drugs that prolong QT interval, induce hypokalemia, hypomagnesemia, or hypocalcemia, or reduce methadone clearance. ECG baseline should be obtained for all patients and evaluate the risk according to QT interval monitoring.

Methadone must be used iwth caution in patients at risk for QT prolongation, taking medications that would prolong the QT interval, electrolyte depletion inducer or history of conduction abnormalities. Normally QT interval prolongation and torsade de pointes is associated with high doses or greater 100 mg/day, however, it has also been observed with lower doses used.