Alpha2-adrenergic agonists for the management of opioid withdrawal

Withdrawal is a necessary step prior to drug-free treatment or as the endpoint of long-term substitution treatment. To assess the effectiveness of interventions involving the use of alpha2-adrenergic agonists compared with placebo, reducing doses of methadone, symptomatic medications or with comparison of different alpha2-adrenergic agonists, for the management of the acute phase of opioid withdrawal. Outcomes included the intensity of signs and symptoms and overall withdrawal syndrome experienced, duration of treatment, occurrence of adverse effects and completion of treatment. We searched the Cochrane Central Register of Controlled Trials (Issue 7, 2013), MEDLINE (1946 to July week 4, 2013), EMBASE (January 1985 to August week 1, 2013), PsycINFO (1806 to July week 5, 2013) and reference lists of articles. We also contacted manufacturers in the field. Randomised controlled trials comparing alpha2-adrenergic agonists (clonidine, lofexidine, guanfacine, tizanidine) with reducing doses of methadone, symptomatic medications or placebo, or comparing different alpha2-adrenergic agonists to modify the signs and symptoms of withdrawal in participants who were opioid dependent. One review author assessed studies for inclusion and undertook data extraction. All review authors decided on inclusion and confirmed the overall process. We included 25 randomised controlled trials, involving 1668 participants. Five studies compared a treatment regimen based on an alpha2-adrenergic agonist with placebo, 12 with a regimen based on reducing doses of methadone, four with symptomatic medications and five compared different alpha2-adrenergic agonists.Alpha2-adrenergic agonists were more effective than placebo in ameliorating withdrawal in terms of the likelihood of severe withdrawal (risk ratio (RR) 0.32, 95% confidence interval (CI) 0.18 to 0.57, 3 studies, 148 participants). Completion of treatment was significantly more likely with alpha2-adrenergic agonists compared with placebo (RR 1.95, 95% CI 1.34 to 2.84, 3 studies, 148 participants).Alpha2-adrenergic agonists were somewhat less effective than reducing doses of methadone in ameliorating withdrawal symptoms, as measured by the likelihood of severe withdrawal (RR 1.18, 95% CI 0.81 to 1.73, 5 studies, 340 participants), peak withdrawal score (standardised mean difference (SMD) 0.22, 95% CI -0.02 to 0.46, 2 studies, 263 participants) and overall withdrawal severity (SMD 0.13, 95% CI -0.24 to 0.49, 3 studies, 119 participant