"Long-acting" olanzapine in maintenance therapy of schizophrenia: A study with plasma levels.

Introduction: This prospective study was performed to evaluate clinical efficacy and tolerability of olanzapine long-acting injection (OLZ-LAI) and the relation between OLZ plasma level (PL) and the clinical outcome in maintenance therapy of schizophrenia.
Material and Methods: Twenty-five chronic schizophrenic outpatients with age ranging from 18 to 65 years were included in this 9-month study. Patients were given a dosage of either 210 or 300 or 405 mg of OLZ-LAI every 28 days. Patients were evaluated at baseline and every four weeks by Brief Psychiatric Rating Scale (BPRS) and Positive and Negative Symptom Scale (PANSS); at the same time, PL of OLZ was determined. The metabolic profile (aspartate aminotransferase, alanine aminotransferase, high-density lipoprotein, low-density lipoprotein, total cholesterol, and glucose levels) was analyzed every two months.
Results: BPRS and total PANSS showed a statistically significant improvement from T2 with a clinical stabilization of psychopathological picture. PL ranged from 4.0 to 78.9 ng/ml (mean 20.59 ng/ml ± 14.66 standard deviation). The coefficient of variation of PLs was related to clinical stabilization. No post-injection delirium sedation syndrome occurred.
Conclusions: Our data reveal the efficacy of OLZ-LAI in maintenance treatment of schizophrenia at lower dosages also in comparison with that of oral therapy. OLZ-LAI seems to be useful for guaranteeing constant PL of the drug. A lesser variation of PL was the most predictable factor associated with maintenance of clinical benefit.