Correlation of fluphenazine plasma levels versus clinical response in patients: a pilot study

Five schizophrenic patients (diagnosed using Research Diagnostic Criteria) under treatment with intramuscular fluphenazine decanoate or oral fluphenazine dihydrochloride had serial plasma fluphenazine and plasma prolactin levels determined by a direct radioimmunoassay method. Clinical state was assessed utilizing the Global Assessment Scale and the Extrapyramidal Symptoms-Neurological Rating Scale. There was no correlation between clinical state and plasma fluphenazine or prolactin levels. All patients under treatment with the depot preparation remained clinically stable with serum fluphenazine levels between 1 and 3 ng/ml. In one patient, who received an intramuscular dose of fluphenazine decanoate, plasma levels were determined using direct radioimmunoassay, extraction followed by radioimmunoassay and gas liquid chromatography-mass spectrometry. There were good correlation between the three methods.