In an open-label, randomized, crossover study, the pharmacokinetics of gepirone immediate-release (gepirone-IR) and different gepirone extended-release (gepirone-ER, types 1, 2, and 3) formulations were compared. Mean maximum concentration (C(max)) was 6.1 ng/mL for gepirone-IR, which was statistically significantly (p < 0.05) higher than that of two of the ER-formulations (3.7 and 3.6 ng/mL, respectively, for types 2 and 3). The mean time to C(max) (mean T(max)) was 1.3 h for gepirone-IR and ranged from 4.8 to 5.6 h for gepirone-ER. The mean area under the curve of concentration versus time (AUC(30)) was similar and not statistically significantly different between gepirone-IR and ER. For the 1-(2-pyrimidinyl)-piperazine (1-PP) metabolite, C(max) and AUC(30) were statistically significantly (p < 0.05) higher and T(max) was lower for gepirone-IR compared with ER. No significant differences in bioavailability were observed between the IR and the three gepirone-ER formulations, indicating that any of the once-daily gepirone-ER formulations could be substituted for gepirone-IR. This study revealed a reduction in the peak-to-trough fluctuations in plasma gepirone concentrations and maintenance of consistent plasma levels with gepirone-ER.
Copyright 2003 Wiley-Liss, Inc. and the American Pharmacists Association