Pharmacokinetics and Pharmacodynamics of Extended-Release Glipizide GITS Compared with Immediate-Release Glipizide in Patients with Type II Diabetes Mellitus

This study was designed to compare the pharmacokinetic and short-term pharmacodynamic profile of extended-release glipizide GITS (Glucotrol XL®) given in a dosage of 20 mg once daily with that of immediate-release glipizide (Glucotrol®) 10 mg twice daily in patients with type II diabetes mellitus, In an open-label, randomized, two-way crossover study, each glipizide formulation was administered for 5 days. Serial blood samples were drawn at baseline and on the 5th day of each treatment phase for measurement of glipizide, glucose, insulin, and C-peptide concentrations. At steady state, the mean C max after immediate-release glipizide was significantly greater than after glipizide GITS, and the t max was considerably shorter. Although the mean C min with glipizide GITS was about 80% higher than with immediate-release glipizide, the mean AUC 0-24 was significantly lower. Despite the lower plasma concentrations with glipizide GITS in this short-term study, the two formulations had similar effects on serum concentrations of glucose, insulin, and C-peptide. The absence of a pronounced peak plasma concentration with the GITS formulation might confer advantages in terms of maintaining clinical effectiveness and reducing the potential to cause adverse effects.