BackgroundPatients with opioid use disorder (OUD) who are managed on methadone often require transition to buprenorphine therapy. Current recommendations require months to gradually taper off of methadone; however, in some cases, the need to transition is urgent. Only a few rapid methadone-to-buprenorphine transitions have been reported and there are no established protocols to guide clinicians in these cases.Case PresentationA 43-year-old man on 95 mg methadone for opioid use disorder experienced cardiac arrest attributable to ventricular fibrillation caused by QTc interval prolongation from methadone. In the hospital, a gradual taper of methadone was initiated but proved intolerable; the patient requested to restart his home dose of methadone and leave against medical advice. A rapid transition was initiated instead. Naltrexone (25 mg) was used to precipitate acute withdrawal followed 1 hour later by a “rescue” with buprenorphine/naloxone (16 mg/4 mg). The Clinical Opiate Withdrawal Score (COWS) peaked at 21 post-naltrexone and fell quickly to 15 within a half-hour of buprenorphine/naloxone administration. The patient was maintained on a total daily dose of 16 mg/4 mg buprenorphine/naloxone through the time of discharge.ConclusionsA patient requiring an urgent taper off of methadone due to adverse cardiac effects successfully transitioned to buprenorphine/naloxone within 2 hours by using naltrexone to precipitate withdrawal followed by a “rescue” with buprenorphine/naloxone. A relatively high dose of 16 mg/4 mg buprenorphine/naloxone successfully arrested withdrawal symptoms. With further refinement, this protocol may be an important technique for urgent methadone-to-buprenorphine transitions in the inpatient setting.