Twenty-four men and 24 women ages 20-77 years received a single 15 mg oral dose of buspirone followed by 4 days of 15 mg tid administration. Plasma concentrations of buspirone and 1-pyrimidinylpiperazine following both single and multiple dosing were determined by RIA and GCMS, respectively. There were no significant differences between the young and elderly of either gender with regard to buspirone AUC, Cmax, Tmax and half-life values. The 1-PP AUC values were higher for young of either gender compared to the corresponding group of elderly subjects and the 1-PP Cmax values were higher for women than men. These differences are unlikely to be of clinical significance. The buspirone and 1-PP AUC values for a dosing interval during multiple dosing are not significantly different than the respective single dose AUC values. Buspirone treatment was well-tolerated by all subjects even though the 45 mg/day dose was 3 times the recommended starting dose in clinical practice. Overall, the lack of marked or consistent differences in buspirone or 1-PP pharmacokinetics in elderly subjects compared to younger subjects of the same gender suggest there is no need to alter the initial dose of buspirone based solely on patient age.