In Vitro ADME Assays & in Vivo ADME Studies

WuXi Biology offers in vitro and in vivo services for drug absorption, distribution, metabolism and excretion (ADME) with state-of-the-art bioanalytical facilities. The scientific staff that oversees these operations is very experienced in characterization of a chemical series and drug candidates. Our services include:

  • Bidirectional Caco-2 Cell Permeability, Pgp Substrate or Inhibitor Identification
  • Protein Binding
  • Plasma Stability
  • Blood Cell Partitioning
  • in vitro Metabolism
  • Metabolite Identification
  • Drug Excretion
  • Pharmacokinetics & Toxicokinetics

Bidirectional Caco-2 Cell Permeability, Pgp Substrate and Inhibitor Identifications

Caco-2 cell permeability (Papp) provides the data to predict absorption of drug candidates across the intestinal epithelial cell barrier. This assay has been validated and confirmed as a robust assay for assessing compound permeability, identification of Pgp (P-glycoprotein) substrates or Pgp inhibitors.

Protein Binding

Plasma protein binding can greatly influence the tissue distribution, clearance, and pharmacological effects of drugs. WuXi Biology performs discovery stage plasma protein binding assays, as well as more thorough studies for regulatory submissions and clinical samples, using equilibrium dialysis or ultrafiltration. Analysis of protein binding samples is typically performed using LC/MS/MS.

Plasma Stability

In vitro plasma stability provides valuable information prior to in vivo PK testing. The samples containing test articles are incubated at 37oC for different time periods. Analysis of plasma stability samples is performed using LC/MS/MS.

Blood Cell Partitioning

The blood–to-plasma concentration ratio of test article is determined in fresh mouse, rat, dog, monkey, and human blood. Percent blood cell distribution is calculated based on the blood and plasma concentrations and hematocrit. Analysis of samples is performed using LC/MS/MS.

In Vitro Metabolism

We provide a full range of in vitro and ex vivo assays utilizing microsomes, S9 fractions, or primary hepatocytes from multiple species, to study drug metabolism. Microsomal stability is commonly used as a discovery tool to predict the extent of hepatic first-pass metabolism. At later stages, it is important to minimize the potential of clinical drug-drug interactions between drug candidates and co-medications. The CYP inhibition potential of new drug candidates can be assessed using a rapid, reliable, and specific CYP inhibition screening method. This method measures the activities of seven major human CYP isozymes (CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, and 3A4) using selective substrates incubated with human liver microsomes and hepatocytes or using recombinant CYP isozymes and fluorescence method for high-through-put screening.

Service Offerings:

  • Metabolic stability and half-life determination
  • High throughput cocktail CYP450 IC50 assay
  • CYP450 isozyme inhibition
  • CYP450 isozyme phenotyping
  • Time-dependent inhibition
  • CYP450 induction
  • Reactive-intermediate trapping

Metabolite identification

We are routinely utilizing the strengths of bioanalysis, LC/MS/MS, and NMR for metabolite identification studies. The goal is to define metabolic pathways for new drug candidates. The studies are often performed in conjunction with mass balance excretion studies, using plasma, urine, or bile samples from mice, rats, dogs, monkeys, or humans. Metabolite identification studies can also be performed in vitro using liver microsomes, hepatocytes, or other preparations from humans or animal species.

Drug Excretion

An excretion study can provide fundamental information about the rates and routes of elimination of a new drug candidate. Mass balance studies are often an important component of regulatory submissions. We perform various mass balance studies in mice, rats, and dogs. Typically, a radio-labeled drug is administered intravenously and/or orally, and excretion of radioactivity is monitored in urine, feces, and occasionally bile. In addition to providing information on the relative rates of excretion in urine and bile, these studies can indicate the percentage of an oral dose systemically absorbed. Further information can be obtained by analyzing mass balance study samples for parent drug and individual metabolites using LC/flow scintillation detection, UV detection or LC/MS/MS to find out routes of elimination of parent compound and its metabolites.

Pharmacokinetics & Toxicokinetics

WuXi Biology has expertise in designing, performing, and interpreting the results of pharmacokinetic studies in all species. Study design and selection of the appropriate model to be used are often customized to meet the project needs. Surgical preparations can be performed, if required. For example, pharmacokinetic study samples might include blood, bile, or other matrices, as well as tissues or tumor specimens that have special bioanalytical requirements. Analysis of pharmacokinetic samples is typically performed using LC/MS/MS. We perform pharmacokinetic studies in mice, rats, dogs, and monkeys for projects at the discovery screening stage (rapid turnaround to meet high-through-put needs), IND-enabling studies, as well as toxicokinetic studies.The data are interpreted our Pharmacokinetics staff using industry-standard WinNonlin software.

We provide the following services:

  • Non-compartmental pharmacokinetics
  • Compartmental pharmacokinetics/simulations
  • Ascending dose (assessment of dose proportionality)
  • Dose linearity after repeat doses
  • Drug interaction studies
  • Pharmacodynamic and PK/PD modeling