NAPLEX Practice Question # 94

NAPLEX Examination.

Practice Question # 94.













Bile acid sequesterants include cholestyramine (Questran®), colestipol (Colestid®), and colesevelam (Welchol®). They are hydrophilic, insoluble anion-exchange resins that are ingested in the form of a slurry or as gel formulation.

  1. Cholestyramine is a resin consisting of trimethylbenzylammonium groups in a large copolymer of styrene and divinylbenzene, whereas colestipol is a copolymer of diethylenetriamine and 1-chloro-2,3-epoxypropane in a hygroscopic powder (Figure 10-14). Colesevelam is a polyallylamine cross-linked with epichlorohydrin and alkylated with 1-bromodecane and (6-bromohexyl)-trimethylammonium bromide in a hydrophilic gel.
  2. These resins are positively charged (cholestyramine, colesevelam) or become positively charged (colestipol) in the small intestines to bind negatively charged bile acids. The bile acids that are normally reabsorbed and returned to the liver are eliminated in the fecal matter. This signals the liver to increase the expression of the LDL receptor to capture more LDL from the blood to recover cholesterol for the synthesis of fresh bile acids.
  3. Bile acid resins are able to lower circulating LDL levels by 10% to 25%; however, this eff ect is not usually sustained because of the ability of the liver for de novo cholesterol synthesis.
  4. Adverse effects seen with bile acid resin use are gastric distress, bloating, and fl atulence. Th ese agents have the ability to reduce the absorption of drugs such as diuretics, thyroxine, warfarin, and statins and have to be administered 1 hr before or 2 hrs aft er other drug ingestion.

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