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.

2,2-DIMETHYLBUTYRIC ACID (HQK-1001) is an orally administered SCFAD (Short Chain Fatty Acid Derivative), which has shown an excellent safety profile and biologic effects on fetal hemoglobin induction and red blood cell production in the laboratory, relevant animal models, and in clinical trials carried out in healthy human subjects as well as patients with sickle cell disease and beta thalassemia. The compound has received Orphan Drug Designation in the United States and Europe for both sickle cell disease and beta thalassemia. HemaQuest Pharmaceuticals was developing HQK-1001 for the oral treatment of sickle cell anaemia and beta thalassaemia. HQK-1001 has been evaluated in phase II trials for beta thalassaemia and sickle cell anaemia.

Epilovastatin is a Lovastatin impurity (Simvastatin Impurity F).