Primary Hyperlipidemia: Colesevelam hydrochloride is a non-absorbed, lipid-lowering polymer that binds bile acids in the intestine, impeding their reabsorption. As the bile acid pool becomes depleted, the hepatic enzyme, cholesterol 7-α-hydroxylase, is upregulated, which increases the conversion of cholesterol to bile acids. This causes an increased demand for cholesterol in the liver cells, resulting in the dual effect of increasing transcription and activity of the cholesterol biosynthetic enzyme, HMG-CoA reductase, and increasing the number of hepatic LDL receptors. These compensatory effects result in increased clearance of LDL-C from the blood, resulting in decreased serum LDL-C levels. Serum TG levels may increase or remain unchanged.

Type 2 Diabetes Mellitus: The mechanism by which WELCHOL improves glycemic control is unknown.

Colesevelam Hydrochoride  is a bile acid sequestrant indicated as an adjunct to diet and exercise to:

1. reduce elevated low-density lipoprotein cholesterol (LDL-C) in adults with primary hyperlipidemia
2. reduce LDL-C levels in boys and postmenarchal girls, 10 to 17 years of age, with heterozygous familial hypercholesterolemia (HeFH), unable to reach LDL-C target levels despite an adequate trial of diet 
3. and lifestyle modification.
   improve glycemic control in adults with type 2 diabetes mellitus