Confusion between methadone and other medications with lookalike names can cause life-threatening errors.
Confusion between methadone and other medications with lookalike names can cause life-threatening errors.
Methadone, a synthetic opioid used for the detoxification and maintenance of narcotic addiction, has steadily gained popularity as a treatment option for moderate-to-severe chronic pain. However, methadone differs from other opioids in several important ways:
Dosing errors
There have been reports of death and life-threatening adverse effects—particularly respiratory depression, QT prolongation, and Torsades de Pointes—in patients taking methadone. These adverse events occurred in patients just starting methadone for pain control and those switched to methadone after being treated for pain with other opioids. The Institute for Safe Medication Practices (ISMP) is aware of two deaths and a near-fatality that resulted from prescribing too large of a starting dose for patients who had previously taken high daily doses of oxycodone controlled release or hydrocodone and acetaminophen. In these cases, the accumulation of methadone during chronic administration was not considered, leading to a buildup of toxic levels.
Errors associated with nomenclature
ISMP has received reports of confusion between methadone and other medications with look-alike names, particularly methylphenidate, dexmethylphenidate, and Mephyton (vitamin K). For example, a 43-year-old patient received methadone 10 mg instead of methylphenidate 10 mg. The prescription was entered correctly into the pharmacy computer system for methylphenidate, but a pharmacy technician accidentally pulled from the shelf a stock bottle of methadone, which was located in the space designated for methylphenidate. The pharmacist performed a final check of the prescription but confirmation bias allowed him to read the stock bottle as methylphenidate even though it was methadone. After taking two tablets, the patient called the pharmacy to complain that she was not feeling well. The patient went to the emergency department, where she was observed for four hours. To prevent life-threatening errors with methadone, pharmacists should consider the following risk-reduction strategies:
Michael J. Gaunt, PharmD, is a medication safety analyst and the editor of ISMP Medication Safety Alert! Community/Ambulatory Care Edition.
This article was originally published in the September 2012 issue of Pharmacy Times.