The second such study evaluated baclofen, a GABA B receptor agonist and antispasmodic medication that reduces mood symptoms in heroin withdrawal [48], and mirtazapine, an antidepressant that enhances noradrenergic and serotonergic transmission and decreases withdrawal symptoms in alcohol-dependent patients [49], especially agitation and insomnia [50]. In this study, separate groups received baclofen (60, 90 mg/day) for 16 days (n=10) or mirtazapine (30 mg/day) for 14 days (n=11) [51] Medication administration began when subjects were outpatients prior to each 8-day inpatient phase. On the first inpatient day of each medication condition, participants smoked active cannabis (baclofen group : 3.3% THC; mirtazapine: 6.2% THC). For the next 3 days, participants could self-administer placebo cannabis (withdrawal phase), followed by 4 days in which they could self-administer active cannabis (relapse phase). During active cannabis smoking, baclofen dose-dependently decreased craving for tobacco and cannabis, but had little effect on mood during abstinence and did not decrease relapse. Mirtazapine improved sleep during abstinence, and robustly increased food intake, but had no effect on withdrawal symptoms and did not decrease cannabis relapse. Overall, this human laboratory study did not find evidence to suggest that either baclofen or mirtazapine show promise for the treatment of cannabis withdrawal.
