Cholesterol-Lowering Zetia Also Works in Liver
That's a newly discovered mechanism for the drug, scientists say
THURSDAY, June 14, 2007 (HealthDay News) -- Research in mice is giving new insight into how the drug ezetimibe (brand name Zetia) works to lower cholesterol. U.S. scientists say the drug is active in the liver, as well as in the intestine.
It was previously thought that the drug works by preventing cells in the lining of the intestine from absorbing cholesterol. This new research, conducted by a team at Wake Forest University Baptist Medical Center in Winston-Salem, N.C., found that the drug also works in the liver, which is involved in making cholesterol and taking it up and "packaging" it for the body's use.
In both the liver and intestine, Zetia targets a protein called NPC1L1, which moves cholesterol into the body's cells. By blocking the protein's actions, the medication prevents absorption of cholesterol.
In the study, which was funded by grants from the American Heart Association and the U.S. National Institutes of Health, the researchers used mice that were genetically engineered to produce NPC1L1 in the liver.
High levels of the protein in the liver resulted in increased cholesterol absorption by liver cells, which led to a major reduction in cholesterol levels in the bile. When the mice were treated with Zetia, cholesterol levels in the bile returned to normal, suggesting that the drug targets NPC1L1 in the liver.
"These findings suggest that in humans, the drug may reduce cholesterol levels in the blood by inhibiting NPC1L1 function in both the intestine and liver," Dr. Liqing Yu, senior researcher and an assistant professor of pathology, section of lipid sciences, said in a prepared statement.
"The fact that Zetia works in two locations is positive, because it makes it more effective as a cholesterol-lowering drug," study lead author Ryan E. Temel said in a prepared statement. "But our research suggests the potential for having too much cholesterol in the bile, which could possibly cause gallstones."
The study was published online Thursday in the Journal of Clinical Investigation and is expected to be in the July 2 print issue.
The American Heart Association has more about cholesterol.