Quetiapine in relapsing schizophrenia: clinical efficacy and effect on monoaminergic parameters

Tolerability, safety and effectiveness of quetiapine in an in-patient group with a relapse of schizophrenia and the possible role of plasma amino acid concentrations, 5-HT parameters and HVA in the prediction of response to treatment were investigated in an open-label baseline-controlled trial of 14 weeks in 21 hospitalized schizophrenic patients. Responders were defined as those patients who exhibit at least a 40% reduction of BPRS total scores. Secondary efficacy measures were the PANSS, the Clinical Global Impression (CGI)-severity scale and the MADRS. Extrapyramidal side-effects were evaluated with the AIMS. Other side-effects were monitored at regular intervals. Amino acids and the derived tryptophan and tyrosine ratios, as well as monoaminergic parameters, were assessed in plasma at baseline and at weeks 3, 6 and 14.

Treatment with quetiapine resulted in the predefined treatment effect in 10 out of the 17 patients who completed at least 4 weeks of treatment. Effect in responders was observed on all efficacy parameters, including lower MADRS scores. No extrapyramidal side-effects emerged. Clinical and biochemical parameters did not predict response to treatment.

This study demonstrates the moderate antipsychotic efficacy of quetiapine on preferentially positive symptoms in a group of relatively young schizophrenics. Some observed changes in biochemical parameters are discussed.