Bile acid sequestrants can potentially bind to concomitant drugs. Single-dose studies evaluated the effects of colesevelam on the pharmacokinetics of glimepiride, glipizide extended-release (ER), and olmesartan medoxomil. Each study enrolled healthy subjects aged 18-45 years. The olmesartan medoxomil study used a randomized adaptive crossover design that initially compared olmesartan medoxomil alone versus simultaneously with colesevelam, then olmesartan medoxomil alone versus 4 hours before colesevelam. The other studies used a three-period crossover design (test drug alone, test drug simultaneously with colesevelam, and test drug 4 hours before colesevelam). For the colesevelam coadministration periods, 3,750 mg once daily was dosed throughout the pharmacokinetic sampling period. After each single dose of test drug, serial blood samples were collected for determination of plasma drug concentrations and calculation of pharmacokinetic parameters. Administering colesevelam simultaneously with glimepiride or glipizide ER resulted in minor reductions (18% and 13%, respectively) in total exposure that were negated by staggering colesevelam dosing by 4 hours. Administering colesevelam simultaneously with olmesartan medoxomil resulted in a major reduction (39%) in olmesartan exposure that was reduced by staggering colesevelam dosing by 4 hours. This reduction in olmesartan exposure is not predicted to have a clinically significant impact on blood pressure control.
Keywords: colesevelam; drug-drug interactions; glimepiride; glipizide; olmesartan medoxomil.
© 2013, The American College of Clinical Pharmacology.