Low serum neuroleptic levels predict relapse in schizophrenic patients.

Relapse occurs in a substantial proportion of schizophrenic patients treated with neuroleptics. The determinants of relapse have been elusive. In our study, low serum neuroleptic levels identified patients who had a relapse during a six-month period. Neuroleptic levels were measured by radioreceptor assay in 61 schizophrenic men and their clinical status was assessed in the subsequent six months. Ten patients had relapses, four showing a worsening of chronic psychotic symptoms and six showing eruption of psychotic symptoms after a period of remission. These ten patients had significantly lower normalized neuroleptic levels than those whose conditions remained stable. The lowest neuroleptic levels occurred in patients who had relapses after a period of remission. Serum neuroleptic levels in drug-responsive patients appear to be a critical determinant of remission. If these observations are replicated, a rational basis may be provided for prescribing and monitoring neuroleptic treatment and perhaps for preventing relapse.