Fluphenazine Blood Levels and Clinical Response

The radioreceptor assay for neuroleptics (NRRA) holds out great theoretical promise as a method for monitoring blood neuroleptic levels, but its practical value is yet to be established. In the present study, 12 psychotic patients were followed longitudinally during treatment with oral (n = 9) and/or depot (N = 7) fluphenazine. Neuroleptic blood levels were determined both by the NRRA and by high performance liquid chromatography utilizing an electrochemical detector (HPLC). Clinical status was monitored by the Brief Psychiatric Rating Scale. Although blood levels were near the limits of sensitivity, the NRRA was able to detect the drug in most samples. HPLC was able to detect fluphenazine in less than 20% of the samples. Detectable blood levels by HPLC were associated with high blood levels by the NRRA. There was a significant correlation between blood levels as measured by the NRRA and clinical improvement. This correlation appears to be independent of the dose or route of administration of fluphenazine. Many patients were followed for several months and a few for over a year. A remarkable constancy of blood levels was found, particularly with depot administration. Given these findings, the NRRA may be an important clinical tool for monitoring patients receiving fluphenazine.