When Tapering Is Not an Option: Transitioning From High-Dose Methadone to Buprenorphine.

Methadone is a commonly used medication for opioid use disorder (OUD) but carries known risks, including corrected QT interval (QTc) prolongation and ventricular arrhythmias. Current guidelines recommend gradual methadone tapering or buprenorphine microdosing when transitioning to buprenorphine to minimize precipitated withdrawal. However, evidence guiding management when methadone must be urgently discontinued because of medical contraindications is limited. We describe a 41-year-old woman with OUD receiving high-dose methadone who presented after cardiac arrest with marked QTc prolongation, hypokalemia, and suspected methadone-associated cardiotoxicity. Given the life-threatening risk of ventricular arrhythmias, methadone was discontinued without tapering. The patient was managed symptomatically with short-acting opioids for withdrawal and was subsequently initiated on buprenorphine approximately 60 hours after her last methadone dose, once moderate withdrawal had developed. Although she experienced transient worsening of withdrawal symptoms after induction, she stabilized within 48 hours and was discharged on maintenance buprenorphine with outpatient follow-up. While gradual tapering remains standard practice, this case demonstrates that complete methadone cessation without tapering, followed by appropriately timed buprenorphine initiation, may be feasible when rapid discontinuation is medically necessary. Careful monitoring, shared decision-making, and symptomatic support remain essential.