Poor response of psychotic symptoms to a single antipsychotic drug appears to be the most common reason for combination of two antipsychotic drugs. Antipsychotic combinations are in clinical practice very common, although there are not sufficient evidences of their efficacy from randomized, controlled trials. We evaluated the efficacy and safety of augmenting amisulpride with quetiapine in patients with sub-optimal response to amisulpride.

In this open-label, non-randomized study, 36 patients who were partially responsive to amisulpride after 4 weeks of treatment were assigned to receive up to 600mg/day quetiapine along with an ongoing stable dose of 800mg/day amisulpride. Patients were evaluated at baseline and at week 1, 3, 6 and 8. Efficacy was assessed using Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impression (CGI) scale and for tolerability we used Simpson-Angus Rating Scale (SAS).

Thirty-one patients completed the study. There was an improvement in the mean scores for PANSS (with more than 30%) and CGI after 8 weeks of treatment, with no major changes in side effect profile.

In patients with a suboptimal response to amisulpride, the addition of quetiapine improved overall positive and negative symptoms of schizophrenia. The combination seems to be safe and well tolerated. Augmentation with quetiapine may provide clinical benefits for patients who are only partially responsive to amisulpride alone. Randomized controlled trials are necessary to evaluate the possible role of this augmentation strategy.