Risperidone-induced increase of plasma norepinephrine is not correlated with symptom improvement in chronic schizophrenia

Background: Previous studies have shown an increase in plasma levels of nor epinephrine (NE) after clozapine treatment of schizophrenia. This effect ha s been suggested to relate to improvement in symptoms. Methods: To test whether other novel antipsychotic drugs have such art effe ct the present experiment examined schizophrenic symptoms and plasma levels of NE before and after 5 weeks of treatment with risperidone or haloperido l. Results: Risperidone, but not haloperidol, significantly increased plasma N E; however, there was no correlation of this effect with clinical improveme nt on any symptom scale. Conclusions: This finding suggests that risperidone shares similar properti es with clozapine in enhancing peripheral NE, bur that these changes in pla sma NE may not be a consistent indicator of atypical antipsychotic drug eff icacy. (C) 1999 Society of Biological Psychiatry.