Mechanism of Action of Cholestyramine on Blood Cholesterol Level
“Cholesterol is probably the sole precursor of bile acids. During normal digestion, bile acids are secreted into the intestines. A major portion of the bile acids is absorbed from the intestinal tract and returned to the liver via the enterohepatic circulation. Only very small amounts of bile acids are found in normal serum. resin adsorbs and combines with the bile acids in the intestine to form an insoluble complex which is excreted in the feces. This results in a partial removal of bile acids from the enterohepatic circulation by preventing their absorption.” Cholestyramine:pharmacology (n.d) Drug bank Retrieved Feb,8,2017, from https://www.drugbank.ca/drugs/DB01432.
“The bile acids, metabolites of cholesterol, are normally efficiently reabsorbed in the jejunum and ileum. Excretion is increased up to tenfold when resins are given, resulting in enhanced conversion of cholesterol to bile acids in liver via 7 alpha hydroxylation, normally controlled by negative feedback by bile acids.
Increased uptake of LDL (Low density Lipoprotein) and IDL from plasma results from up-regulation of LDL receptors, particularly in liver” retrieved from Mary & John (2007). Agents used in hyperlipidemia. In Bertram G.K (10th edition) Basic and Clinical pharmacology (pp.570) Singapore.
Therefore a loss of bile acids leads to an increase in the conversion of cholesterol into bile acids in the liver and a compensatory increase in hepatic LDL receptors that results in reduction of LDL and cholesterol serum level.
Cited Works
Bertram G.K (2007) Basic and Clinical pharmacology (10th edition) Singapore McGraw Hill
Wishart DS, Knox C, Guo AC, Shrivastava S, Hassanali M, Stothard P, Chang Z, Woolsey J. DrugBank: a comprehensive resource for in silico drug discovery and exploration. Nucleic Acids Res. 2006 Jan 1;34(Database issue):D668-72. …