Two weeks' quetiapine treatment for schizophrenia, drug-induced psychosis and borderline personality disorder: a naturalistic study with drug plasma levels.

OBJECTIVE: To evaluate clinical outcomes and the tolerability of 2 weeks' quetiapine (QTP) treatment for hospitalised patients in a naturalistic setting. METHODS: Patients with schizophrenia (n = 18), drug-induced psychosis (n = 10; 3 cocaine, 4 hashish and marijuana, and 3 all three substances) or borderline personality disorder (n = 13), were diagnosed by two expert clinicians on the basis of an unstructured clinical interview, and were treated with QTP (250-1000 mg/day). The subjects were then clinically assessed at baseline, and after 7 and 15 days, using the Brief Psychiatric Rating Scale, the Positive and Negative Symptoms Scale (PANSS) and the Hamilton Rating Scale for Depression. At the end of the study, plasma QTP levels were determined and examined in relation to clinical outcome and tolerability. RESULTS: The mean scores of each rating scale were significantly lower at the end of the study in the population as a whole, and within each diagnostic group. The percentage improvement was significantly greater in the patients with drug-induced psychosis than in those with schizophrenia (42.4 +/- 9.1% versus 23.6 +/- 13.5%). QTP was well tolerated, and the incidence of extrapyramidal side effects was low. There was a linear correlation between plasma levels and dose/kg of QTP (r = 0.31; p < 0.05). The improvement in PANSS significantly correlated with plasma levels and dose/kg in each diagnostic category (Spearman's coefficient was 0.75 [p < 0.01] for schizophrenia and borderline personality disorder, and was 0.68 [p < 0.05] for drug-induced psychosis). CONCLUSION: The results suggest that 2 weeks' QTP treatment may improve the clinical outcome of psychotic re-exacerbation phases in different diagnostic categories and indicate that QTP improves clinical outcome in drug-induced psychosis, as QTP levels correlated with the clinical improvement measured by PANSS.