[Olanzapine efficacy in the treatment of cocaine abuse in methadone maintenance patients. Interaction with plasma levels].

INTRODUCTION

The aim of this study was to evaluate the efficacy of the treatment with antipsychotic olanzapine in cocaine abuse methadone patients. The decrease or interruption of cocaine consume as well as the possible pharmacokinetic interaction between olanzapine and methadone were studied.

MATERIAL AND

METHODS

Patients (n= 21) include in a methadone maintenance program (14 months), with DSM-IV criteria for opioid and cocaine dependence and without schizophrenic diagnostic, were treated with olanzapine 5 to 10 mg/day. The therapeutic outcomes were assessed by personal interviews, cocaine consumption, changes of consumption patrons (via of administration) and secondary effects to olanzapine. Withdrawal symptoms were measured by means of the abbreviate version of the scale of Gossop. Cocaine used was measured by urine analysis (enzymoimmnuoassay). The possible pharmacokinetic interaction between olanzapine and methadone was measured in plasma before and during the treatment in 15 patients.

RESULTS

Olanzapine combined with methadone in cocaine abusers was well tolerated in an important proportion of patients. Moreover the consumption of cocaine was decreased or stopped in 53,2% of the patients. In addition, no withdrawal syndrome was observed in any patients. Furthermore the ratios of methadone plasma levels did not change in relation to the dose before and during the treatment, suggesting a lack of pharmacokinetic interaction between methadone and olanzapine.

CONCLUSIONS

In conclusion the results of this preliminary study, led us to advance that olanzapine could be a useful treatment for cocaine abuse at least in patients in a Methadone Maintenance Program, with the advantage of not to induce any pharmacokinetic interaction with methadone.