Active Ingredient in Zetia
The active ingredient in Zetia is ezetimibe, a selective cholesterol absorption inhibitor that works by blocking the Niemann-Pick C1-Like 1 (NPC1L1) protein in the small intestine. 1
Chemical Composition and Formulation
The chemical name of ezetimibe is 1-(4-fluorophenyl)-3(R)-[3-(4-fluorophenyl)-3(S)-hydroxypropyl]-4(S)-(4-hydroxyphenyl)-2-azetidinone, with an empirical formula of C24H21F2NO3 and molecular weight of 409.4 1
Each Zetia tablet contains 10 mg of ezetimibe as the sole active pharmaceutical ingredient 1
The inactive ingredients include lactose monohydrate, croscarmellose sodium, hypromellose, sodium lauryl sulfate, crospovidone, microcrystalline cellulose, and magnesium stearate 1
Mechanism of Action
Ezetimibe reduces blood cholesterol by inhibiting the absorption of cholesterol by the small intestine through blocking the sterol transporter NPC1L1, which is involved in the intestinal uptake of cholesterol and phytosterols 1, 2
The drug localizes at the brush border of the small intestine and inhibits cholesterol absorption, leading to decreased delivery of intestinal cholesterol to the liver 1
This mechanism causes a reduction of hepatic cholesterol stores and an increase in LDL receptors, resulting in enhanced clearance of cholesterol from the blood 1
Ezetimibe's mechanism is distinct from statins (which inhibit cholesterol synthesis) and bile acid sequestrants (which bind bile acids) 3
Clinical Efficacy
As monotherapy, ezetimibe reduces LDL-C by approximately 18% 2, 4
When combined with statin therapy, ezetimibe provides an additional 25% incremental reduction in LDL-C beyond statin therapy alone 2, 4
In clinical trials, ezetimibe inhibited intestinal cholesterol absorption by 54% compared with placebo 1