DMPK Assays

ADME Assays

In Vitro and In Vivo ADME Services

WuXi Biology offers in vitro and in vivo services for drug absorption, distribution, metabolism and excretion (ADME) studies using state-of-the-art bioanalytical facilities and instrumentation. Our services include:

Bidirectional Caco-2 Cell Permeability, P-gp Substrate and Inhibitor Identification

Caco-2 cell permeability testing provides 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 and for identification of P-gp (P-glycoprotein) substrates and/or P-gp 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. Samples containing test articles are incubated at 37C for different time periods. Analysis of plasma stability is performed using LC-MS/MS.

Blood Cell Partitioning

The blood–to-plasma concentration ratio of a 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 value. 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 liver microsomes, S9 fractions, or primary hepatocytes from multiple species to assess drug metabolism of a test article. 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 methods 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 assay

Metabolite identification

We utilize LC-MS/MS and NMR for metabolite identification studies. The goal is to define metabolic pathways for new drug candidates. 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 radiolabeled 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.

DMPK

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 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 offer pharmacokinetic studies in mice, rats, dogs, and monkeys for projects at the discovery screening stage (rapid turnaround to meet high-throughput needs), IND-enabling studies, as well as toxicokinetic studies. Data are interpreted by our pharmacokinetic experts 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