Prediction of treatment response in schizophrenia: clinical use of neuroleptic blood levels.

The relationship between clinical response and plasma neuroleptic levels in schizophrenia is unclear. Apart from the inadequacy of the plasma neuroleptic assay method, resistance to neuroleptic treatment in some schizophrenics presents a serious problem in studies looking into the plasma drug level versus clinical response correlation. Previous studies have suggested a very wide range of plasma neuroleptic levels in responders. At present, plasma neuroleptic level does not predict clinical response in schizophrenics in general, but may have application in special situations such as suspected drug toxicity, neuroleptic resistance or idiosyncratic response to neuroleptic drugs.