In healthy rats that naturally make a lot of cholesterol in their liver, the drug ezetimibe didn’t lower their blood cholesterol at all.

When diabetic rats ate a high-cholesterol diet and were given a drug called ezetimibe, their blood cholesterol dropped dramatically, and their liver made more of a key cholesterol-making enzyme—not by making more of its instructions, but by using the existing instructions more efficiently.

In rats without thyroid glands that ate a high-cholesterol diet, a drug called ezetimibe lowered their blood cholesterol and brought back their liver’s cholesterol-making enzyme to normal levels, but didn’t change the receptor that clears cholesterol from the blood.

Ezetimibe works best when the liver isn’t making much cholesterol on its own and the gut is absorbing a lot from food.

Ezetimibe helps lower bad cholesterol by stopping your gut from absorbing it, and even though it works well and doesn't cost much, doctors don't use it as much as they could.