Drug Interactions between colesevelam and deferasirox

GENERALLY AVOID: Coadministration with cholestyramine may decrease the bioavailability and efficacy of deferasirox. The mechanism involves binding of cholestyramine to deferasirox and its glucuronide metabolites, which are secreted into the bile. This interferes with the enterohepatic recycling of deferasirox by preventing intestinal deconjugation of the glucuronide metabolites and subsequent reabsorption. In healthy volunteers, administration of cholestyramine (12 grams twice daily) 4 and 10 hours after a single dose of deferasirox resulted in a 45% decrease in deferasirox systemic exposure (AUC). The interaction has not been studied with other bile acid sequestrants.

MANAGEMENT: The concomitant use of deferasirox with cholestyramine should generally be avoided. Otherwise, consideration should be given to increasing the initial dosage of deferasirox by 50% with subsequent adjustments made according to serum ferritin levels and clinical response. It is not known whether other bile acid sequestrants interact similarly with deferasirox.