Age and Serum Fluphenazine Concentrations

Abstract

Fluphenazine (FPZ) is relatively commonly used in geriatric patients. However, the effects of advanced age on FPZ pharmacokinetics are poorly understood. To test the hypothesis that FPZ concentration/dose ratios are positively associated with age, we retrospectively studied 43 patients who were on stable doses of FPZ and had serum concentrations determined by HPLC during their hospitalization. Their ages ranged from 20 yrs to 87 yrs. In 11 patients FPZ concentrations were below the limit of detection. The ages and FPZ doses of patients with detectable FPZ concentrations overlapped those of patients with nondetectable FPZ. In patients with detectable FPZ, the correlation between age and FPZ concentration/dose was not significant (r=.15). In aged patients, lower doses of FPZ may not be generally necessary to achieve concentrations equivalent to those in younger patients.