Ezetimibe is an anti-hyperlipidemic medication which is used to lower cholesterol levels. Specifically, it appears to bind to a critical mediator of cholesterol absorption, the Niemann-Pick C1-Like 1 (NPC1L1) protein on the gastrointestinal tract epithelial cells as well as in hepatocytes. Ezetimibe is in a class of lipid-lowering compounds that selectively inhibits the intestinal absorption of cholesterol and related phytosterols. Ezetimibe, administered alone is indicated as adjunctive therapy to diet for the reduction of elevated total-C, LDL-C, and Apo B in patients with primary (heterozygous familial and non-familial) hypercholesterolemia. It is also used in combination therapy with HMG-CoA reductase inhibitors. Ezetimibe has a mechanism of action that differs from those of other classes of cholesterol-reducing compounds (HMG-CoA reductase inhibitors, bile acid sequestrants, fibric acid derivatives, and plant stanols). Ezetimibe does not inhibit cholesterol synthesis in the liver, or increase bile acid excretion but instead localizes and appears to act 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 HMG-CoA reductase inhibitors.

Atorvastatin calcium (LIPITOR®) is a pyrrole and heptanoic acid derivative, a synthetic lipid-lowering agent. Atorvastatin is a selective, competitive inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase. This enzyme catalyzes the conversion of HMG-CoA to mevalonate, an early and rate-limiting step in cholesterol biosynthesis. Atorvastatin is used to reduce serum levels of LDL(low-density lipoprotein)-cholesterol; apolipoprotein B; and triglycerides and to increase serum levels of HDL(high-density lipoprotein)-cholesterol in the treatment of hyperlipidemias and prevention of cardiovascular disease in patients with multiple risk factors.

Simvastatin is a HMG-CoA Reductase Inhibitor that is FDA approved for the treatment of hypercholesterolemia and for the reduction in the risk of cardiac heart disease mortality and cardiovascular events. It reduces levels of "bad" cholesterol (low-density lipoprotein, or LDL) and triglycerides in the blood, while increasing levels of "good" cholesterol (high-density lipoprotein, or HDL). Common adverse reactions include abdominal pain, constipation, nausea, headache, upper respiratory infection. Cases of myopathy/rhabdomyolysis have been observed with simvastatin co-administered with lipid-modifying doses ( ≥ 1 g/day niacin) of niacin-containing products. The risk of myopathy, including rhabdomyolysis, is increased by concomitant administration of amiodarone, dronedarone, ranolazine, or calcium channel blockers such as verapamil, diltiazem, or amlodipine.

Lovastatin acid is an active metabolite of hypolipidemic drug Lovastatin. Lovastatin acid inhibits HMG-CoA reductase. This enzyme catalyzes the conversion of HMG-CoA to mevalonate, which is an early and rate limiting step in the biosynthesis of cholesterol. Lovastatin has been shown to reduce both normal and elevated low-density lipoprotein cholesterol (LDL-C). Lovastatin in approved for prevention of cardiovascular events and hypercholesterolemia. Off-label use of lovastatin includes treatmetn of diabetic dyslipidemia, familial dysbetalipoproteinemia, familial combined hyperlipidemia, or nephrotic hyperlipidemia. Lovastatin was tested in clinical trials agains radioation injury during therapy of prostate cancer.

Gemfibrozil, a fibric acid antilipemic agent similar to clofibrate, is used to treat hyperlipoproteinemia and as a second-line therapy for type IIb hypercholesterolemia. It acts to reduce triglyceride levels, reduce VLDL levels, reduce LDL levels (moderately), and increase HDL levels (moderately). Gemfibrozil increases the activity of extrahepatic lipoprotein lipase (LL), thereby increasing lipoprotein triglyceride lipolysis. It does so by activating Peroxisome proliferator-activated receptor-alpha (PPARα) 'transcription factor ligand', a receptor that is involved in metabolism of carbohydrates and fats, as well as adipose tissue differentiation. This increase in the synthesis of lipoprotein lipase thereby increases the clearance of triglycerides. Chylomicrons are degraded, VLDLs are converted to LDLs, and LDLs are converted to HDL. This is accompanied by a slight increase in secretion of lipids into the bile and ultimately the intestine. Gemfibrozil also inhibits the synthesis and increases the clearance of apolipoprotein B, a carrier molecule for VLDL. Gemfibrozil is most commonly sold as the brand name, Lopid. Other brand names include Jezil and Gen-Fibro.

Liothyronine (CYTOMEL®) is a T3 thyroid hormone normally synthesized and secreted by the thyroid gland in much smaller quantities than its prohormone thyroxine (T4). Most T3 is derived from peripheral monodeiodination of T4 at the 5' position of the outer ring of the iodothyronine nucleus. The hormone finally delivered and used by the tissues is mainly T3. The mechanisms by which thyroid hormones exert their physiologic action are not well understood. These hormones enhance oxygen consumption by most tissues of the body, increase the basal metabolic rate and the metabolism of carbohydrates, lipids, and proteins. Thus, they exert a profound influence on every organ system in the body and are of particular importance in the development of the central nervous system. Thyroid hormone drugs are indicated: as the replacement or supplemental therapy in patients with hypothyroidism of any etiology; as pituitary thyroid-stimulating hormone (TSH) suppressants, in the treatment or prevention of various types of euthyroid goiters; as diagnostic agents in suppression tests to differentiate suspected mild hyperthyroidism or thyroid gland autonomy.

Niacin (also known as vitamin B3 and nicotinic acid) is bio converted to nicotinamide which is further converted to nicotinamide adenine dinucleotide (NAD+) and the hydride equivalent (NADH) which are coenzymes necessary for tissue metabolism, lipid metabolism, and glycogenolysis. Niacin (but not nicotinamide) in gram doses reduces LDL-C, Apo B, Lp(a), TG, and TC, and increases HDL-C. The increase in HDL-C is associated with an increase in apolipoprotein A-I (Apo A-I) and a shift in the distribution of HDL subfractions. These shifts include an increase in the HDL2:HDL3 ratio, and an elevation in lipoprotein A-I (Lp A-I, an HDL-C particle containing only Apo A-I). The mechanism by which niacin alters lipid profiles is not completely understood and may involve several actions, including partial inhibition of release of free fatty acids from adipose tissue, and increased lipoprotein lipase activity (which may increase the rate of chylomicron triglyceride removal from plasma). Niacin decreases the rate of hepatic synthesis of VLDL-C and LDL-C, and does not appear to affect fecal excretion of fats, sterols, or bile acids. As an adjunct to diet, the efficacy of niacin and lovastatin in improving lipid profiles (either individually, or in combination with each other, or niacin in combination with other statins) for the treatment of dyslipidemia has been well documented. The effect of combined therapy with niacin and lovastatin on cardiovascular morbidity and mortality has not been determined. In addition, preliminary reports suggest that niacin causes favorable LDL particle size transformations, although the clinical relevance of this effect is not yet clear. April 15, 2016: Based on several large cardiovascular outcome trials including AIM-HIGH, ACCORD, and HPS2-THRIVE, the FDA decided that "scientific evidence no longer supports the conclusion that a drug-induced reduction in triglyceride levels and/or increase in HDL-cholesterol levels in statin-treated patients results in a reduction in the risk of cardiovascular events" Consistent with this conclusion, the FDA has determined that the benefits of niacin ER tablets for coadministration with statins no longer outweigh the risks, and the approval for this indication should be withdrawn.

Turofexorate Isopropyl (XL335) is a potent, selective, and orally bioavailable FXR agonist. Binds to the ligand-binding domain (LBD) of human FXR. Turofexorate Isopropyl resides in a predominately hydrophobic pocket with only a few polar atoms making contact with WAY-362450. Turofexorate Isopropyl promotes transcription of the human BSEP, human SHP, and mouse IBABP genes utilizing reporter constructs with EC50 of 17, 230, and 33 nM, respectively in promoter assays. Turofexorate Isopropyl had been in phase I clinical trials for the treatment of hyperlipidemia. This compound was originally discovered by Exelixis Pharmaceuticals, then licensed to Wyeth (now a wholly-owned subsidiary of Pfizer). However, the studies were discontinued.

Acifran (AY-25,712), an uncommercialized Ayerst compound exerting lipid-lowering activity in vivo, has been shown to also elicit similar effects as niacin in preliminary clinical testing and has been shown to bind to both high affinity (HM74A; GPR109A) and low affinity (HM74; GPR109B) niacin receptors. The EC50 values of the separated acifran enantiomers for the GPR109a and 109b receptors showed that, as with acifran itself, the (+)-enantiomers were essentially twice as active as the racemic mixtures, whereas the activity of the (-)-enantiomers was more variable and highly dependent on purity. S-enantiomer of acifran is the active principle. All of the activity of racemic acifran could be attributed to the (S)-enantiomer, and hence, from this precedent, (+)-enantiomers would be assigned to the S-configuration. However, the absolute configuration was not confirmed experimentally.

Avasimibe (CI 1011) is a potent ACAT (Acyl-CoA:cholesterol acyltransferase) inhibitor. Avasimibe inhibits both ACAT1 and ACAT2 isoforms. Avasimibe was in development by Parke-Davis (now Pfizer) in the US for the treatment of atherosclerosis and hyperlipidaemia. Avasimibe was in phase III studies and more than 1300 patients had been treated for up to one year, however, in October 2003, Pfizer announced that development had been discontinued.