Glipizide pharmacokinetics in young and elderly volunteers

The effects of aging on the pharmacokinetics of glipizide were studied. Ten healthy young men (24.9 +/- 1.9 years of age) and 10 healthy older men (74.4 +/- 7.9 years of age) each ingested a single 5-mg tablet of glipizide after an overnight fast. Blood samples were obtained immediately before drug ingestion and at 10, 20, 30, 45, 60, 90, and 120 minutes and at 3, 4, 6, 8, 10, 12, and 24 hours after drug ingestion. Serum samples were assayed for glipizide content by a modified high-pressure liquid chromatographic method. Clearance, volume of distribution at steady state, and half-life were estimated from the serum concentration-time curve data. Area under the concentration-time curve and area under the moments curve were calculated using the trapezoidal rule. The mean values for young and older subjects for time to peak concentration (2.1 versus 2.5 hours), peak concentrations (465 versus 399 micrograms/mL), elimination half-life (4.2 versus 4.0 hours), clearance (38.8 versus 38.1 mL/min), and distribution volume at steady state (12.5 versus 14.3 L) were not significant. However, two older individuals had a markedly prolonged time to peak concentration (six to eight hours). For 8 of the 20 subjects a more prolonged terminal half-life may have existed. Further study is required to determine whether significant pharmacokinetic differences between young and elderly subjects appear with multiple dosing of glipizide.