Organic Anion Transporter 2–Mediated Hepatic Uptake Contributes to the Clearance of High-Permeability–Low-Molecular-Weight Acid and Zwitterion Drugs: Evaluation Using 25 Drugs

Abstract

High-permeability-low-molecular-weight acids/zwitterions [i.e., extended clearance classification system class 1A (ECCS 1A) drugs] are considered to be cleared by metabolism with a minimal role of membrane transporters in their hepatic clearance. However, a marked disconnect in the in vitro-in vivo (IVIV) translation of hepatic clearance is often noted for these drugs. Metabolic rates measured using human liver microsomes and primary hepatocytes tend to underpredict. Here, we evaluated the role of organic anion transporter 2 (OAT2)-mediated hepatic uptake in the clearance of ECCS 1A drugs. For a set of 25 ECCS 1A drugs, in vitro transport activity was assessed using transporter-transfected cells and primary human hepatocytes. All but two drugs showed substrate affinity to OAT2, whereas four (bromfenac, entacapone, fluorescein, and nateglinide) also showed OATP1B1 activity in transfected cells. Most of these drugs (21 of 25) showed active uptake by plated human hepatocytes, with rifamycin SV (pan-transporter inhibitor) reducing the uptake by about 25%-95%. Metabolic turnover was estimated for 19 drugs after a few showed no measurable substrate depletion in liver microsomal incubations. IVIV extrapolation using in vitro data was evaluated to project human hepatic clearance of OAT2-alone substrates considering 1) uptake transport only, 2) metabolism only, and 3) transporter-enzyme interplay (extended clearance model). The transporter-enzyme interplay approach achieved improved prediction accuracy (average fold error = 1.9 and bias = 0.93) compared with the other two approaches. In conclusion, this study provides functional evidence for the role of OAT2-mediated hepatic uptake in determining the pharmacokinetics of several clinically important ECCS 1A drugs.

Quantitative Proteomics and Mechanistic Modeling of Transporter‐Mediated Disposition in Nonalcoholic Fatty Liver Disease

“…In line with our observation, recent reports suggested that organic solute transporter alpha/beta (OSTα/β) expression is considerably upregulated in NAFLD liver, and that N‐linked glycosylation does not influence its trafficking to the plasma membrane and function . The observation that OAT2 expression is decreased significantly in NASH is of interest, as recent studies have shown that its interplay with CYPs impacts the PK of several drugs such as R/S‐warfarin and tolbutamide …”

Quantitative Contribution of Six Major Transporters to the Hepatic Uptake of Drugs: “SLC-Phenotyping” Using Primary Human Hepatocytes

“…Our previous evaluation of transporter-mediated DDIs per ECCS class validated the predominant role of OATPs in the hepatic clearance of class 1B and 3B drugs (Varma et al, 2015(Varma et al, , 2017aEl-Kattan et al, 2016). More recent studies clearly demonstrated OAT2-mediated uptake contribution to the clearance of class 1A drugs (Bi et al, 2018a,b;Kimoto et al, 2018). Additionally, drugs such as sumatriptan, morphine, and ondansetron, which showed association of pharmacokinetic variability with the SLC22A1 genotype, belong to ECCS classes 2 and 4 (Tzvetkov et al, 2013;Matthaei et al, 2016).…”

“…Clearly, hepatic clearance of high-MW acids/zwitterions (ECCS class 1B/3B; e.g., statins) is associated with OATP1B1/1B3-mediated hepatic uptake (Shitara et al, 2013;Varma et al, 2015Varma et al, , 2017b. Results of our recent studies have shown that the majority of ECCS class 1A drugs (low-MW acids/zwitterions; e.g., warfarin, tolbutamide) are substrates to OAT2 (Bi et al, 2018b;Kimoto et al, 2018). Similarly, ECCS class 4 drugs (low-permeability bases/neutrals; e.g., metformin) potentially involve OCT1 in their hepatic disposition (El-Kattan and Varma, 2018).…”

Impairment of Intestinal Monocarboxylate Transporter 6 Function and Expression in Diabetic Rats Induced by Combination of High-Fat Diet and Low Dose of Streptozocin: Involvement of Butyrate–Peroxisome Proliferator-Activated Receptor-γ Activation

“…Bumetanide is used as probe substrate to estimate the function of MCT6 (Murakami et al, 2005), although it is also a substrate or inhibitor of other transporters in intestinal tissues, such as organic anion transporter 2 (OAT2), sodium-potassium-2chloride cotransporter 1 (NKCC1), multidrug resistance protein 4 (MRP4), and BCRP (Burckhardt, 2012;Tollner et al, 2015;Romermann et al, 2017;Nigam, 2018). Several reports have shown that neither OAT2 nor MRP4 mediate nateglinide transport (Uchida et al, 2007;Kimoto et al, 2018). No evidence has demonstrated that NKCC1 and BCRP mediate nateglinide transport.…”