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.

Tenivastatin (well known as simvastatin acid or simvastatin hydroxy acid) is a pharmacologically active metabolite, which is formed in the mammalian organism from lactone prodrug, simvastatin. Tenivastatin is a potent reversible inhibitor of HMGCR (HMG-CoA reductase), reduces cholesterol synthesis and increases low-density lipoprotein (LDL) receptors on cell membranes of liver and extrahepatic tissues. It is also a substrate of organic anion transporting polypeptide 1B1 (OATP1B1/Oatp2), an influx transporter expressed on the sinusoidal membrane of hepatocytes. Recent studies have shown that OATP1B1 plays a clinically important role in the hepatic elimination of several drugs including statins, via mediating the hepatic uptake. In addition, was discovered, that the tenivastatin was a substrate of another transporter protein, human organic anion transporting polypeptide 3A1 (OATP3A1), which is predominately expressed in the heart. Presence of OATP3A1 in cardiomyocytes suggested that transporter could modulate the exposure of cardiac tissue to simvastatin acid due to its enrichment in cardiomyocytes. Increases in the uptake of simvastatin acid by OATP3A1 when combined with OATP substrates suggest the potential for drug-drug interactions that could influence clinical outcomes.