Ezetimibe is a white, crystalline powder that is freely to very soluble in ethanol, methanol, and acetone and practically insoluble in water. Its structural formula is:

 
(click image for full-size original) Atorvastatin is [R-(R*, R*)]-2-(4-fluorophenyl)-ß, δ-dihydroxy-5-(1-methylethyl)-3-phenyl-4-[(phenylamino) carbonyl]-1H-pyrrole-1-heptanoic acid, calcium salt (2:1).

Atorvastatin calcium is a white to off-white amorphous powder that is very slightly soluble in water, insoluble in acetonitrile, and soluble in methanol. The empirical formula of atorvastatin calcium is (C33 H34 FN2 O5 )2 Ca. The molecular weight of atorvastatin calcium is 1155.37. Its structural formula is:

 
(click image for full-size original) LIPTRUZET is available for oral use as tablets containing 10 mg of ezetimibe and: 10.34 mg of atorvastatin calcium, equivalent to 10 mg of atorvastatin (LIPTRUZET 10 mg/10 mg); 20.68 mg of atorvastatin calcium, equivalent to 20 mg of atorvastatin (LIPTRUZET 10 mg/20 mg); 41.37 mg of atorvastatin calcium, equivalent to 40 mg of atorvastatin (LIPTRUZET 10 mg/40 mg); or 82.73 mg of atorvastatin calcium, equivalent to 80 mg of atorvastatin (LIPTRUZET 10 mg/80 mg). Each film-coated tablet of LIPTRUZET contains the following inactive ingredients: lactose monohydrate, microcrystalline cellulose, croscarmellose sodium, povidone, sodium lauryl sulfate, magnesium stearate, lactose anhydrous, hydroxypropyl cellulose, and sodium bicarbonate. In addition, the film coating contains the following inactive ingredients: hydroxypropyl cellulose, hypromellose, titanium dioxide, and carnauba wax.

12 CLINICAL PHARMACOLOGY12.1 Mechanism of ActionLIPTRUZET

Plasma cholesterol is derived from intestinal absorption and endogenous synthesis. LIPTRUZET contains ezetimibe and atorvastatin, two lipid-lowering compounds with complementary mechanisms of action.

Ezetimibe

Ezetimibe reduces blood cholesterol by inhibiting the absorption of cholesterol by the small intestine. The molecular target of ezetimibe has been shown to be the sterol transporter, Niemann-Pick C1-Like 1 (NPC1L1), which is involved in the intestinal uptake of cholesterol and phytosterols. In a 2-week clinical study in 18 hypercholesterolemic patients, ezetimibe inhibited intestinal cholesterol absorption by 54%, compared with placebo. Ezetimibe had no clinically meaningful effect on the plasma concentrations of the fat-soluble vitamins A, D, and E and did not impair adrenocortical steroid hormone production.

Ezetimibe does not inhibit cholesterol synthesis in the liver or increase bile acid excretion. Ezetimibe localizes at the brush border of the small intestine and inhibits the absorption of cholesterol, leading to a decrease in the delivery of intestinal cholesterol to the liver. This causes a reduction of hepatic cholesterol stores and an increase in clearance of cholesterol from the blood; this distinct mechanism is complementary to that of statins [see Clinical Studies (14)].

Atorvastatin
In animal models, atorvastatin lowers plasma cholesterol and lipoprotein levels by inhibiting HMG-CoA reductase and cholesterol synthesis in the liver and by increasing the number of he