High-Dose Methadone Transfer to Buprenorphine in Outpatient Settings

Abstract

Historically, methadone has been the favoured medication for treating opioid dependency and numerous trials have demonstrated that higher prescribed methadone doses result in reduced illicit drug use (Trafton et al. 2006). However, high-level dosing is also associated with increased risk of serious health problems, including the potentially fatal cardiac arrhythmia, torsades de pointes (Pimentel and Mayo 2007). Buprenorphine, also now used for the treatment of opioid dependence, is less likely to produce these side effects and some cardiologists now request that methadone patients with prolonged QTc be transferred to this agent (Wedam et al. 2007). Owing to the partial agonist and antagonist actions of buprenorphine, transfer is not a straightforward procedure because the differing modes of action can lead to withdrawal symptoms, as buprenorphine displaces methadone at the μ-receptors. To avoid the risk of precipitated withdrawal, current guidelines (Lintzeris et al. 2006) recommend that methadone doses should be tapered to 30 mg/day before patient transfer to buprenorphine. This process may lead to risk of relapse to illicit drug use, which makes extensive dose reductions unachievable (Wallace 2011). Attempts to identify efficient transfer procedures for high-dose methadone patients through the elucidation of clinical symptoms and biochemical measures that indicate when transfer is optimal have produced debate but little evidence as to which measures most reliably predict the optimal time for the first buprenorphine administration. Many patients are now being transferred to buprenorphine and this is most commonly achieved by admitting the patient to hospital, an expensive but effective option. Outpatient transfer has been described and we sought to define appropriate measures to identify when a patient can safely be given a first dose of buprenorphine in an outpatient department (OPD) setting. Despite recommendations to taper methadone, there are conflicting opinions as to whether a correlation between methadone dose and blood serum concentrations exists. Studies by Okruhlica and colleagues (2005) and Wolff and colleagues (1991) support a linear relationship only at doses <80 mg. Adelson and colleagues (2007) report good correlation in patients receiving methadone doses of 40–290 mg and without illicit substance use. With a doseInt J Ment Health Addiction (2015) 13:194–203 DOI 10.1007/s11469-014-9521-2