Rate-Determining and Rate-Limiting Steps in the Clearance and Excretion of a Potent and Selective p21-Activated Kinase Inhibitor: A Case Study of Rapid Hepatic Uptake and Slow Elimination in Rat

Title:Rate-Determining and Rate-Limiting Steps in the Clearance and Excretion of a Potent and Selective p21-Activated Kinase Inhibitor: A Case Study of Rapid Hepatic Uptake and Slow Elimination in Rat

Volume: 10 Issue: 2

Author(s): Kirsten Messick, Matthew Wright, S. Cyrus Khojasteh, Lesley J. Murray, Joachim Rudolf, James J. Crawford, Wendy Lee, Shannon Liu, Nicole Valle, Peter W. Fan, Matthew Durk, Robert T. Cass, Teresa Mulder, Ning Liu, Hank La, M. Allan Jaochico and Jacob Z. Chen

Affiliation:

Keywords: Enzyme-transporter interplay, hepatic uptake, intestinal secretion, IVIVC, Organic cation transporter.

Abstract: Background: Significant under-prediction of in vivo clearance in rat was observed for a potent p21-activated kinase (PAK1) inhibitor, GNE1.

Objective: Rate-determining (rapid uptake) and rate-limiting (slow excretion) steps in systemic clearance and elimination of GNE1, respectively, were evaluated to better understand the cause of the in vitro-in vivo (IVIV) disconnect.

Methods: A series of in vivo, ex vivo, and in vitro experiments were carried out: 1) the role of organic cation transporters (Oct or Slc22a) was investigated in transporter knock-out and wild-type animals with or without 1-aminobenzotriazole (ABT) pretreatment; 2) the concentration-dependent hepatic extraction ratio was determined in isolated perfused rat liver; and 3) excreta were collected from both bile duct cannulated and non-cannulated rats after intravenous injection.

Results: After intravenous dosing, the rate-determining step in clearance was found to be mediated by the active uptake transporter, Oct1. In cannulated rats, biliary and renal clearance of GNE1 accounted for only approximately 14 and 16% of the total clearance, respectively. N-acetylation, an important metabolic pathway, accounted for only about 10% of the total dose. In non-cannulated rats, the majority of the dose was recovered in feces as unchanged parent (up to 91%) overnight following intravenous administration.

Conclusion: Because the clearance of GNE1 is mediated through uptake transporters rather than metabolism, the extrahepatic expression of Oct1 in kidney and intestine in rat likely plays an important role in the IVIV disconnect in hepatic clearance prediction. The slow process of intestinal secretion is the rate-limiting step for in vivo clearance of GNE1.

Cite this article as:

Messick Kirsten, Wright Matthew, Cyrus Khojasteh S., Murray J. Lesley, Rudolf Joachim, Crawford J. James, Lee Wendy, Liu Shannon, Valle Nicole, Fan W. Peter, Durk Matthew, Cass T. Robert, Mulder Teresa, Liu Ning, La Hank, Allan Jaochico M. and Chen Z. Jacob, Rate-Determining and Rate-Limiting Steps in the Clearance and Excretion of a Potent and Selective p21-Activated Kinase Inhibitor: A Case Study of Rapid Hepatic Uptake and Slow Elimination in Rat, Drug Metabolism Letters 2016; 10 (2) . https://dx.doi.org/10.2174/1872312810666160411144358