Olanzapine as long-term adjunctive therapy in treatment-resistant bipolar disorder

The aim of this study was to estimate the longterm effectiveness of olanzap ine as adjunctive therapy in patients with bipolar disorder who exhibited a n inadequate response to mood stabilizers. Twenty-three Research Diagnostic Criteria (RDC) patients with bipolar I and II were assessed by means of th e Schedule for Affective Disorders and Schizophrenia and entered if they ga ve their consent to participate. All of them had experienced frequent relap ses, residual subsyndromal symptoms, and inadequate responses to other drug s, such as lithium, valproate, or carbamazepine. While maintaining other dr ugs, they all received open-label, increasing doses of olanzapine, until ac hieving clinical response. Other drugs were maintained. The patients were a ssessed several consecutive times from baseline to the endpoint with the Cl inical Global Impressions (CGI) scale for use in bipolar illness. Records o f recurrences, hospitalizations, and side effects were also collected. The last-observation-carried-forward analysis showed that there was a significa nt reduction of CGI scores after the introduction of olanzapine, either in manic symptoms (p = 0.0015), depressive symptoms(p = 0.0063), or global sym ptoms (p = 0.0003). The most frequent adverse events were somnolence (17%) and weight gain (13%). The mean dose of olanzapine at the end of the 43-wee k follow-up was 8.1 mg/day. Olanzapine may be a useful medication for the l ong-term adjunctive treatment of patients with bipolar disorder who exhibit a poor response to mood stabilizers, such as lithium, valproate, or carbam azepine. These results suggest mood-stablizing properties of olanzapine.