Treatment of methamphetamine-induced psychosis: a double-blind randomized controlled trial comparing haloperidol and quetiapine.

RATIONALE: To our knowledge, only a few double-blind randomized controlled trials with antipsychotic drugs have been conducted to examine the treatment of methamphetamine-induced psychosis (MAP).

OBJECTIVES: The aims of this study are to compare the antipsychotic and adverse events of quetiapine, an atypical antipsychotic drug, to haloperidol, a standard treatment for primary psychotic disorder, in individuals with MAP.

METHODS: Eighty individuals with MAP were randomly assigned into two groups, i.e. treatment with quetiapine (n = 36) and haloperidol (n = 44). Sixty-eight patients (85 %) completed the study protocol, i.e. treatment with quetiapine at least 100 mg per day or haloperidol at least 2 mg per day orally once a day for 4 weeks. The doses were increased every 5 days until no psychotic symptom was observed from the Positive and Negative Syndrome Scale (PANSS). Data were analysed by survival analysis with Cox's proportional regression analysis, general estimating equations and log-rank tests.

RESULTS: Thirty-two (89 %) subjects from the quetiapine group and 37 subjects (84 %) from the haloperidol group met the remission criteria at the end of the study. Baseline PANSS total scores of quetiapine and haloperidol groups were 82.4 ± 16.6 and 90.0 ± 18.4, respectively (mean ± SD; p = 0.06). The change-from-baseline scores were -47.8 for the quetiapine group and -53.2 for the haloperidol group. There were no significant differences between the antipsychotic effects (coefficient value = -2.6, p = 0.32, 95%CI = -7.6, 2.5) and the adverse effects of quetiapine and haloperidol.

CONCLUSIONS: Quetiapine may be used as an antipsychotic treatment for MAP with comparable therapeutic effects and adverse events to treatment with classical antipsychotic drugs.