Objectives: To compare the efficacy of memantine with buprenorphine in the suppression of naloxone-precipitated acute withdrawal in heroin-dependent male subjects in an inpatient setting.
Setting: Inpatient unit of tertiary level deaddiction facility.
Participants: Forty-five treatment-seeking heroin-dependent males.
Interventions: Subjects stabilized on 650 mg of dextropropoxyphene for 5 days were randomly divided into two groups on the sixth day: group A (n=25) received 20 mg of memantine with buprenorphineplacebo, and group B (n=20) received 2 mg of buprenorphine with memantine placebo. Acute withdrawals were precipitated with naloxone (0.4 mg, intravenously) and were assessed using subjective and objective opioid withdrawal scales (SOWS and OOWS) and two separate visual analogue scales (VASs) for pain and dysphoria at baseline prior to test drug administration and again after the precipitation of acute withdrawal.
Main outcome measures: Severity ofprecipitated opioid withdrawals.
Results: Baseline opioid withdrawal symptoms in both groups did not differ significantly. After the precipitation of acute withdrawal, there were no significant differences between subjects in both groups on OOWS and both VASs but showed significant difference on SOWS. When changes in ratings from baseline (and after naloxone-precipitated acute withdrawal) were compared between the two groups, a significant difference in the change in SOWS scores was observed with greater decrease in withdrawal scores in the buprenorphine group.
Conclusions: Memantine has comparable efficacy to buprenorphine in the suppression of objective signs of naloxone-precipitated acute opioid withdrawal; however, its role in the suppression of subjective symptoms is debatable.