Plasma levels of parent drug and metabolites in patients receiving oral and depot fluphenazine

Abstract

We evaluated the metabolism of fluphenazine (FLU) in patients treated with either the oral form of FLU or with fluphenazine decanoate (FD). Samples for both patient populations were analyzed using four different radioimmunoassays developed in our laboratories for fluphenazine, fluphenazine sulfoxide (FS), 7-hydroxy fluphenazine (7OHFLU), and fluphenazine N-oxide (FLUNO). In patients receiving oral FLU the levels of FS and 7OHFLU were significantly higher than levels of FLU. In patients receiving FD, the levels of metabolites were significantly lower than FLU levels. This supports the view that drug metabolism is likely to be a more important factor for patients treated with an oral as opposed to a depot phenothiazine neuroleptic.