Comparative Pharmacokinetics Studies of Immediate- and Modified-Release Formulations of Glipizide in Pigs and Dogs

The utility of pigs as preclinical animals for pharmaceutical development was assessed by evaluating the pharmacokinetics and pharmacodynamics of glipizide (Glucotrol®) following oral administration of immediate-release (IR) and modified-release (MR) formulations. Doses of 10 and 30 mg were administered to six male pigs in a crossover design. Blood samples were collected at selected time-points up to 48 h after dose. Relative to the IR formulation, the time to reach the maximum concentration (tmax) was delayed with the MR formulation from 1.3 to 8.7 h with the 10 mg dose and to 6.2 h with the 30 mg dose. The relative bioavailability (BA) was approximately 92% at 10 mg and 79% at 30 mg dose. The area under the curve of the plasma concentration versus time curve (AUC) increased nearly proportionally with the dose. Interanimal coefficient of variation (CV) in AUC ranged from approximately 40% to 60%. Blood glucose results suggest that pigs demonstrate formulation-dependent response to glipizide. Compared with the pigs, the 10 mg MR formulation in dogs showed a higher AUC CV of approximately 80%, a tmax of 5.5 h, and a lower relative BA of 18%. These data indicate that the MR formulation performed less consistently in dogs as compared with humans, whereas the porcine absorption kinetics and BA were consistent with published clinical data.