Pumping new life into preclinical pharmacokinetics: exploring the pharmacokinetic application of ex vivo organ perfusion

Abstract

In conclusion, in this thesis we aimed to study to pharmacokinetic application of pressure driven normothermic organ perfusion. Using a novel pressure driven perfusion machine, we endeavoured to bridge the fields of transplantation and pharmacology. Our studies demonstrated the utilization of NMP to examine various drug PK processes such as the hepatic first pass effect, hepatic clearance, biliary excretion, transporter function and DDI using porcine and human explanted diseased livers. The use of porcine livers was an appropriate substitute for human livers to mechanistically study transporter contribution in drug uptake, drug excretion and to study DDI. These studies enabled the investigation of OATP1B1/1B3 mediated DDI, with results aligning closely with clinical data. Moreover, explanted diseased human livers showed to be suitable for perfusion research and can serve as a basis to explore the differences in hepatic handling of drugs for patients with different types of hepatic impairment. Hepatic clearance of rosuvastatin and digoxin showed to be the most affected by cirrhosis while no major differences were observed for the renally cleared drugs metformin and furosemide. The 3-fold lower portal flow in cirrhotic livers showed to diminish the hepatic extraction of rosuvastatin showing the importance of portal flow in a preclinical model to determine hepatic clearance. Furthermore, optimalisation of the liver perfusion model was studied by infusion of a (un)conjugated bile acid pool to replicate physiological conditions for a more accurate assessment of hepatic PK processes. This approach demonstrated that the infusion of (un)conjugated bile acids alleviated the burden of the de novo bile acid synthesis and enhanced liver function pointing towards potential advancements in liver preservation and transplantation techniques. The possibilities of the pressure driven perfusion system are numerous, as we demonstrated the development and application of multi-organ perfusion to understand the interplay between the intestine and liver by characterization of the first-pass effect and pre-systemic CYP3A4 metabolism. Use of perfusion showed to be an excellent tool to study drug

concentrations in blood flows and tissues which are otherwise impossible to reach, thereby generating a novel and in-depth insights into the ADME profile of drugs.