Drug Interactions between Welchol and Zetia

ADJUST DOSING INTERVAL: Bile acid sequestrants may reduce the systemic exposure and therapeutic effects of ezetimibe. The exact mechanism has not been thoroughly described in the literature, but may involve a reduction in absorption and/or interference with enterohepatic recirculation of ezetimibe by the bile acid sequestrant. In a study of adult subjects with low-density lipoprotein cholesterol (LDL-C) levels of greater than or equal to 130 mg/dL, concomitant administration of cholestyramine (4 g twice daily) with ezetimibe (10 mg) reduced the systemic exposure (AUC) of total ezetimibe (ezetimibe plus its pharmacologically active metabolite) by approximately 55%. In contrast, some clinical trials involving colesevelam with ezetimibe have indicated that the pair may be able to be administered simultaneously without affecting ezetimibe's efficacy. Specific data on the effects of other bile acid sequestrants on the AUC of ezetimibe are not available.

MANAGEMENT: Ezetimibe's labeling indicates that use with a bile acid sequestrant may decrease ezetimibe's efficacy and recommends administration at least 2 hours before or 4 hours after the bile acid sequestrant. However, the labeling for some colesevelam products indicate that this pair can be separated as described in ezetimibe's product information or administered together.