Whether there is value in obtaining a screening ECG in a patient receiving an initial dose of methadone in the ED is unclear, and this practice is controversial even among methadone clinics. However, some of the excess death in patients taking methadone may be explained by the dysrhythmogenic potential of methadone.4 An ECG therefore may elucidate a correctable cause in methadone patients presenting with syncope.
Administering methadone to patients with documented QT prolongation must weigh the risk of methadone’s conduction effects against the substantial risks of illicit opioid self-administration. For some patients at-risk for TdP, it may be preferable to use buprenorphine if possible, since it does not carry the same cardiac effects as methadone.1,5 Such therapy requires referral to a physician licensed to prescribe this medication.
How should admitted patients be managed?
While administration of methadone for withdrawal or maintenance therapy in the ED is acceptable, outpatient prescribing of methadone for these reasons is not legal, and only federally regulated clinics may engage in this practice. Hospitalized patients who are enrolled in an MMT program should have their daily methadone dose confirmed and continued—as long as the patient has not lost tolerance. Patients not participating in an MMT program can receive up to 3 days of methadone in the hospital, even if the practitioner is not registered to provide methadone.6 For these patients, it is recommended that the physician order a low dose of methadone and also consult with an addiction specialist to determine whether the patient should continue on MMT maintenance or undergo detoxification.
It is important to note that methadone may be prescribed for pain, but its use in the ED for this purpose is strongly discouraged, especially in patients who have never received methadone previously. For admitted patients requiring such potent opioid analgesia, consultation with a pain service or, when indicated, a palliative care/hospice specialist is warranted as the dosing intervals are different in each setting, and the risk of respiratory depression is high.
Case Conclusion
As requested by the MMT clinic, the patient was administered methadone 185 mg orally in the ED, though a dose of 10 mg would have been sufficient to prevent withdrawal. Unfortunately, the EP did not appreciate the relationship of the markedly prolonged QTc and the methadone, which should have prompted a dose reduction.
Evaluation of the patient’s electrolyte levels, which included magnesium and potassium, were normal. An ECG was repeated 24 hours later and revealed a persistent, but improved, QT interval at 505 ms. The remainder of the syncope workup was negative. Because the patient had no additional symptoms or events during her stay, she was discharged. At discharge, the EP followed up with the MMT clinic to discuss lowering the patient’s daily methadone dose, as well as close cardiology follow-up.
Dr Rao is the chief of the division of medical toxicology at New York Presbyterian Hospital/Weill Cornell Medical Center, New York. Dr Nelson, editor of “Case Studies in Toxicology,” is a professor in the department of emergency medicine and director of the medical toxicology fellowship program at the New York University School of Medicine and the New York City Poison Control Center. He is also associate editor, toxicology, of the EMERGENCY MEDICINE editorial board.