A number of nonabsorbed bile acid binding resins may be given to reduce enterohepatic circulation of bile acids and in doing so reduce serum cholesterol. These agents may also interfere with drug absorption.

Bile acid binding resins include cholestyramine, colestipol and colesevelam.


Mechanism of action: anion exchange polymer


Drugs typically affected: lipophilic, anionic drugs


Some drugs affected: thiazides, Ocaliva (obeticholic acid), warfarin


Drugs not affected: phenytoin


When to suspect:

(1) less than expected therapeutic effect

(2) recorded interaction

(3) unexplained reduction in serum drug levels


If both the bile acid binding resin and target drugs must be given, then the doses should be separated by as much time as possible, preferrably by more than 4 hours.

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