Solute carrier organic anion transporter family member 1B1 (OATP1B1), Solute carrier organic anion transporter family member 1B3 (OATP1B3), and ATP-binding cassette sub-family B member 1 (P-gp) (OATP1B1/OATP1B3/P-gp)

The transporters OATP1B1 (SLCO1B1), OATP1B3 (SLCO1B3), and P-glycoprotein (P-gp/ABCB1) are critical determinants of the pharmacokinetics and safety profile of simvastatin and its active metabolite, simvastatin acid [1, 2, 3]. OATP1B1 and OATP1B3 are located on the sinusoidal membrane of hepatocytes and are responsible for the hepatic uptake of simvastatin acid, which is necessary for the drug to inhibit HMG-CoA reductase [3, 5]. P-glycoprotein is an efflux pump found in the intestine and liver that limits the absorption and facilitates the excretion of simvastatin [2]. Genetic variations in the SLCO1B1 gene, particularly the c.521T>C polymorphism, significantly reduce the transport activity of OATP1B1, leading to markedly increased systemic exposure to simvastatin acid [4]. This elevated exposure is strongly associated with an increased risk of statin-induced myopathy and potentially fatal rhabdomyolysis [3, 4]. Furthermore, pharmacological inhibition of these transporters by concomitant medications like cyclosporine or clarithromycin can precipitate severe drug-drug interactions [3]. Consequently, these transporters are primary targets for pharmacogenomic screening and clinical management to prevent adverse drug reactions during lipid-lowering therapy [3].

Other names

SLCO1B1SLCO1B3ABCB1MDR1P-glycoproteinOrganic anion-transporting polypeptide 1B1Organic anion-transporting polypeptide 1B3OATP-COATP8LST-1

These transporters regulate the pharmacokinetics of simvastatin by mediating its hepatic uptake (OATP1B1/1B3) and intestinal/biliary efflux (P-gp). OATP1B1 and OATP1B3 facilitate the entry of the active simvastatin acid into hepatocytes to reach its therapeutic target, HMG-CoA reductase, while P-gp limits systemic bioavailability and aids in excretion [3, 5].