"The goal of the study was to characterize population pharmacokinetics (PPK) for perphenazine in patients with schizophrenia from the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE). (n = 156) received 8 to 32 mg of perphenazine daily for 14 to 600 days for a total of 421 plasma concentrations measurements," scientists writing in the Journal of Clinical Pharmacology report (see also Schizophrenia).

"Nonlinear mixed-effects modeling was used to determine PPK characteristics of perphenazine. One- and 2-compartment models with various random effect implementations and mixture distributions were evaluated. function values and goodness-of-fit plots were used as model selection criteria. Age, weight, sex, race, smoking, and concomitant medications were evaluated as covariates. A 1-compartment linear model with proportional error best described the data. The population mean clearance and volume of distribution for perphenazine were 483 L/h and 18 200 L, respectively. Race and smoking status had significant impacts on perphenazine clearance estimates. In addition, the estimated population mean clearance was 48% higher in nonsmoking African Americans than in nonsmoking other races (512 L/h vs 346 L/h). Active smokers eliminated perphenazine 159 L/h faster than nonsmokers in each race," wrote Y.Y. Jin and colleagues, Indiana University.

The researchers concluded: "Clearances for smoking African Americans versus smokers in other races were 671 L/h versus 505 L/h, respectively."

Jin and colleagues published their study in the Journal of Clinical Pharmacology (Population Pharmacokinetics of Perphenazine in Schizophrenia Patients From CATIE: Impact of Race and Smoking. Journal of Clinical Pharmacology, 2010;50(1):73-80).

Additional information can be obtained by contacting R.R. Bies, Indiana University, Div Clin Pharmacol, Sch Medical, 1001 W 10th St W7138, Indianapolis, IN 46204, USA.

The publisher of the Journal of Clinical Pharmacology can be contacted at: Sage Publications Inc., 2455 Teller Rd., Thousand Oaks, CA 91320, USA.