Pharmacokinetics of buspirone extended-release tablets: A single-dose study

The objective of this study is to evaluate the absorption of buspirone and its biotransformation to 1-(2-pyrimidinyl) piperazine (1-PP) from two diffe rent extended-release (ER) formulations of buspirone HCl tablets (12-hour a nd 24-hour in vitro release) and from a commercially available immediate- r elease (IR) tablet. A single dose of the 30 mg ER tablets was compared with two doses of the 15 mgIR tablet administered 12 hours apart. Eighteen heal thy male subjects participated in this randomized, open-label, three-treatm ent crossover study. Blood samples were obtained at 22 time points from pre dose (0 hour) until 36 hours postdose, and plasma concentration of buspiron e and 1-PP was determined by LC/tandem mass spectrometry method. The pharma cokinetic parameters AUG(0-t), AUC(0-infinity), C-max, t(max), K-e, and t(1 /2), were calculated and statistically analyzed. The results indicated exte nded release of buspirone from the two test products in vivo with a 70% to 90% greater bioavailability in comparison with the IR formulation. The bioa vailability of 1-PP from ER formulations appears to be equal to that from t he IR formulation. Both buspirone ER tablets successfully delivered bioavai lable buspirone with a reduction in peak drug and metabolite plasma levels, prolonged buspirone plasma concentrations, and decreased ratio of 1-PP to buspirone concentration with less intersubject variation when evaluated as a single-dose study in healthy human subjects.