Abstract
The development of a novel drug is a highly cost-intensive and risky process and many drug candidates fail on the way to final approval. An important task during this development is to investigate the absorption, distribution, metabolism, and excretion (ADME) of a drug candidate. To investigate these parameters appropriately and to prevent failure of the drug candidate, predictive in vitro systems are needed. As the liver plays an important role in drug metabolism, hepatic in vitro models are of special interest.
In this thesis, we assessed the usability of HepaRG cells with a knock-out (KO) of pregnane X receptor (PXR) and/or constitutive androstane receptor (CAR) for cytochrome P450 (CYP450) induction studies. Using this system, it was possible to delineate CYP3A4 and CYP2B6 induction mechanisms.
Further, we showed that multi-well array three-dimensional (3D) spheroid cultures of primary human hepatocytes (PHH) can be successfully applied for the determination of turnover of slowly metabolized drugs. This system increased the detectable dynamic range of clearance in comparison to the gold standard PHH in suspension but also to single spheroid cultures and HepaRG sandwich cultures. The dynamic range and the prediction accuracy of human clearance was equal in comparison to a random co-culture and a micro-patterned co-culture (MPCC) system.
In conclusion, we evaluated novel hepatic in vitro systems for drug metabolism and pharmacokinetic (DMPK) studies which can help to improve the drug development process and reduce the translational gap.
