Effectiveness and Safety of Haloperidol Add-on Methadone in Acute Opium Withdrawal Symptoms of Opioid-dependent Patients: A Double-blind Randomized Placebo-controlled Clinical Trial

The aim of this double-blind clinical trial was to evaluate the efficacy and safety of haloperidol on acute opioid withdrawal symptoms.

In this randomized double-blind clinical trial, fifty-two eligible patients were assigned to two groups according to previous opioid consumption, low dose (LD) and high dose (HD). Then, patients in each group were randomly assigned to one of the two subgroups of haloperidol or placebo. Patients in the haloperidol subgroup in LD group received 2.5 mg and in HD group received 5 mg/day haloperidol with methadone. Methadone was discontinued ten days after the beginning of the study and haloperidol or placebo continued for up to two weeks after methadone discontinuation. The severity of opioid withdrawal symptoms was assessed with the Objective Opioid Withdrawal Scale (OOWS) every other day.

Although both treatment protocols either in LD or HD opioid consumption groups significantly increased the score of the OOWS over the trial period (all subgroups, P < 0.001), the combination of 2.5 mg/day of haloperidol and methadone in LD opioid consumption group showed a significant superiority over methadone alone in decreasing opium withdrawal symptoms during the study (P = 0.001). The frequency of adverse effects was comparable between two treatment protocols in both groups (P > 0.05).

The results of this study suggest that 2.5 mg/day of haloperidol may be an effective adjuvant agent in the management of opium withdrawal symptoms in patients with LD opioid consumption. Nevertheless, results of larger controlled trials are needed before recommendation for a broad clinical application can be made