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Bioavailability of a compound is mainly determined by absorption, distribution, metabolism and excretion (ADME), which can be evaluated by a series of in vitro assays. In small molecule drug discovery the typical goal is to identify a low molecular weight compound which can be effectively administered via an oral route. The fraction of a dose after drug administration that reaches the general circulation intact is defined as its bioavailability.

There is a significant advantage to obtaining in vitro ADME data as early as possible in the drug discovery process. For example, hepatic metabolism is a primary determinant of pharmacokinetic behavior and rapid first-pass metabolism is a major cause of low bioavailability. In vitro ADME results serve as good indicators as to whether a compound will be bioavailable and assists in eliminating failures early in the development process. It also serves as a useful guide for later stage studies.

Eurofins offers a diverse set of in vitro ADME assays which, if applied early in the drug discovery process, can be used to prioritize compounds based on these properties and to select those compounds likely to have high bioavailability for further development.



Assessment assays for bioavailability:

  • Aqueous Solubility
  • Partition Coefficient
  • Protein Binding / Blood Partitioning
  • In vitro Absorption
  • In vitro Metabolism
  • Caco-2 Permeability
  • P-gp Substrate Determination


Figure 1. Compound stability in hepatocytes

Cryopreserved human hepatocytes were pooled from 10 donors and counted at 10e6 viable cells/ml. The parent drug was added at 0.5µM and incubated for 0, 30, 60, 90, and 120 minutes and assayed using HPLC-MS/MS detection.