Sidney Chang

Fluphenazine pharmacokinetics and therapeutic response

We conducted a double-blind study of therapeutic outcome versus mean steady-state levels in 29 newly admitted schizophrenic and schizoaffective patients who were treated with a constant dose of fluphenazine HCl over a 2-week period. Both an upper and lower end of the therapeutic window were suggested by three nonresponders whose plasma levels were above 2.8 ng per ml and by two nonresponders and one partial responder whose plasma levels were below 0.2 ng per ml. The mean terminal half-life of fluphenazine (±SD) was 16.4±13.3 h. We found that concomitant use of benztropin mesylate during the initial 4 weeks of fluphenazine treatment did not significantly alter fluphenazine plasma levels.

Prediction of in vivo red cell/plasma Li+ ratios by in vitro methods

Two incubation procedures were used for the determination, in vitro, of the steady‐state Li+ ratio between red cells and external media. The Li+ ratio in vitra determined prior to Li+ therapy correlates significantly with the subsequent ratio in vivo between red cells and plasma in patients treated with Li+. The Li+ ratio determined in vitro in patients during Li+ therapy was significantly higher than the value determined during the pretreatment, drug‐free period but correlated significantly with Li+ ratios in vivo. The in vitro procedure used thus could be applied in the prediction of the in vivo Li+ ratio, and possibly of the response to Li+, in patients before treatment is begun. It also could be used for studies on abnormalities and on the genetics of Li+ transport in affective illness.