The efficacy and safety of once-daily quetiapine extended release in patients with schizophrenia switched from other antipsychotics: an open-label study in Chinese population

BACKGROUND: Non-adherence to antipsychotic medication in schizophrenic patients is common and associated with symptom relapse and poorer long-term outcomes. The risk factors for treatment non-adherence include dosing frequency and complexity. Besides, slower dose titration in an acute schizophrenic episode may lead to attenuated efficacy. Therefore, the convenient dosage regimen and rapid initiation scheme of quetiapine extended release (XR) were expected to provide better effectiveness and promote adherence in patients with schizophrenia. This study was implemented to assess the efficacy and safety of once-daily quetiapine XR in schizophrenic patients with switched from other antipsychotics which were suboptimal due to insufficient efficacy or tolerability. METHODS: This was a 12-week, open-label study conducted in the Chinese population in Taiwan. Patients who had a score of 4 (moderate) or greater on any of the 7 items of the Positive and Negative Syndrome Scale (PANSS) Positive Symptom Subscale and needed to switch from previous antipsychotics were recruited. Quetiapine XR was administered at 300 mg on day 1, 600 mg on day 2 and up to 800 mg after day 2. From day 8 until the end of the study, the dose of quetiapine XR was adjusted within 400-800 mg per day, depending on the clinical response and tolerance of the patients. The variable of the primary outcome was the change from baseline to Week 12 in PANSS total and subscale scores. Secondary outcome was the baseline-to-endpoint difference in the Clinical Global Impression-Severity (CGI-S) scores of the participants. RESULTS: Sixty-one patients were recruited and 55.7% of them completed the study. The mean changes in the PANSS total score and CGI-S score showed significant improvement (−18.4, p < .001 and −1.0, p < .001, respectively). Four patients (6.7%) experienced adverse events including headache, exacerbation of psychosis and dysuria. The use of concomitant anticholinergics decreased from 15.0% to 8.3%. CONCLUSIONS: The results of our investigation implicated that quetiapine XR was an effective and well tolerated alternative for Chinese schizophrenic patients with previous suboptimal treatment. Future large-scale studies are warranted to validate our results. TRIAL REGISTRATION: ClinicalTrials.gov ID NCT02142556. Registered 15 May 2014.