Transitioning From Methadone to Buprenorphine in a Patient With Prolonged QTc Interval in the Setting of Acute Liver Failure: A Case Report.

Abstract

Background: Methadone, a mu-opioid receptor agonist, is one of 3 FDA-approved medications for opioid use disorder (OUD). Acute liver dysfunction can impair hepatic metabolism and increase sedation risk. Methadone can induce QT prolongation, which increases the risk of Torsades de Pointes, more commonly in patients on doses higher than 100 mg. Options for managing methadone-related QT prolongation include lowering the methadone dose or switching to buprenorphine, a partial mu-opioid agonist also FDA-approved for OUD. Precipitated withdrawal poses a challenge when transitioning from methadone to buprenorphine, and acute impaired hepatic metabolism of methadone contributes to uncertainty about how long clinicians must wait before initiating full-dose buprenorphine. Limited guidance exists on this transition.

Case summary: We report the case of a 37-year-old man with hepatitis C, alcohol use disorder, and OUD in long-term remission on methadone 210 mg daily who was transferred to a quaternary care center for liver transplant evaluation due to acute liver failure. On presentation, an EKG showed a QTc of 785 milliseconds prompting discontinuation of methadone. Oxycodone 10 mg every 6 hours as needed was started, with nearly full amelioration of withdrawal symptoms. Eleven days after the last methadone dose, and 12 hours after the last oxycodone dose, buprenorphine 8 mg SL was administered, and the patient experienced severe precipitated withdrawal.

Discussion: This case report highlights the challenge of estimating methadone half-life in a patient with severe acute liver dysfunction who needs to switch from methadone to buprenorphine. A buprenorphine low-dose induction strategy may reduce the risk and severity of precipitated withdrawal.