Effects of Dextromethorphan on reducing methadone dosage in opium addicts undergoing methadone maintenance therapy: A double blind randomized clinical trial

BACKGROUND: Dextromethorphan (DM) is an N-methyl-D-aspartate (NMDA) receptor antagonist that may be useful during opiate addiction process, especially in reducing methadone consumption in methadone maintenance therapy (MMT). The goal of the current study was to evaluate the effects of oral administration of DM on reducing methadone dose in MMT used to treat illicit opioid drug abuse. METHODS: A double-blinded randomized clinical trial was designed. Seventy two opiate abusers undergoing MMT were randomly divided into two groups. Participants in the intervention group were medicated by DM while those in the control group received placebo. After a 6-week follow-up, methadone consumption dosage, quality of life (QOL) and withdrawal symptoms were assessed and compared between the two groups by repeated measure ANOVA statistical test. RESULTS: The mean of methadone consumption in the DM and control groups were 62.7 mg/day (52.7-72.7) and 70.4 mg/day (60.4-80.4), respectively. No statistically significant difference was found between the two groups among the four evaluations made (F = 1.192, P = 0.279). There were not any significant differences in withdrawal symptoms between the two groups (P > 0.05). Total mean scores of QOL in the intervention and control groups were 84.8 (78.7-90.8) and 77.8 (71.8-83.7) (P > 0.05), respectively. CONCLUSIONS: Although DM might be useful for opioid dependence treatment, results of the current study did not reveal any statistically significant differences. Therefore, further studies exploring this possibility are needed.