IVAL Services

In Vitro Drug Metabolism Services

Metabolic Stability

Using Liver Microsomes

Metabolic stability is a key drug property, which is important for both drug administration regiment design as well as toxicity. Species comparison in metabolic stability allows the determination of which animal species is the most appropriate model for the estimation of human metabolic stability of the test article. The use of liver microsomes allows the evaluation of metabolic stability as results of phase I oxidation. The use of hepatocytes allows the evaluation of both phase I oxidation and phase II conjugation.

Drug-drug Interaction Assay

Using Liver Microsomes and Hepatocytes

The FDA recommends the evaluation of new drug candidates for drug-drug interactions. The identity of the metabolites allows the assignment of major metabolic pathways, which will facilitate experimental design for the evaluation of drug-drug interaction potential. For instance, if a drug forms phase 1 oxidation metabolites, then P450 pathways may be involved in its metabolism. Experiments concerning P450 pathway identification, P450 inhibition and induction are studies that would need to be performed. Choose your in vitro system from our inventory of liver microsomes and cryopreserved hepatocytes: see catalog listing

Liver Microsomes:
  • Human
  • Cynomolgus monkey
  • Rhesus monkey
  • Sprague-Dawley rat
  • CD-1 mouse
  • Beagle Dog
Cryopreserved Hepatocytes:
  • Human
  • Cynomolgus monkey

Pathway Determination Assay


Identification of the major pathways involved in the metabolism of a drug will be performed using liver microsomes in the presence of selective inhibitors for the 8 major CYP isoforms, (tabulated below). The ability of an inhibitor to inhibit metabolism of the drug would indicate that the pathway inhibited by the inhibitor is involved in metabolism. Quantification of the parent chemical and its metabolites will be performed using HPLC-LC/MS and the percent contribution of a specific CYP isoform towards metabolism of the test article is reported. see catalog listing

P450 Inhibition Assay

Utilizing Luminescent or LC/MS Assays

A major mechanism of drug-drug interaction is the inhibition of drug metabolizing enzymes by a drug, thereby inhibiting the metabolism of co-administered drugs, which are substrates of the inhibited pathways. This can be performed using liver microsomes (human/animal) and hepatocytes readily available at IVAL. Choose between luminescent or LC/MS validated protocols. see catalog listing

P450 Induction Assay

Utilizing Luminescent or LC/MS Assays

Enzyme induction is a major mechanism of pharmacokinetic drug-drug interactions. A drug that induces a specific drug metabolizing enzyme (e.g. a specific P450 isoform) would have the potential to enhance the metabolism of a co-administered drug that is a substrate of the induced pathway. Enzyme induction studies are generally performed using human hepatocytes. This approach is recommended by the U.S. FDA. Choose between validated luminescent or LC/MS assays.see catalog listing

Adverse Drug Effects Assay

Hepatotoxicity, CYP3A Inhibition and Induction

In Vitro ADMET Laboratories (IVAL) now offers a proprietary high-throughput ADE assay in primary human hepatocytes. This robot assisted HTS assay provides reproducible and accurate results within 10 days of test article receipt. Our ADE assay addresses the 3 most critical questions in drug development, namely, hepatotoxicity, CYP3A inhibition and induction. Hepatotoxicity assay measures cell viability (ATP content) and apoptosis (caspase activity) in response to drug treatment. CYP3A4 inhibition and induction assays measure CYP3A enzyme activity in presence of a luciferin-based CYP3A4 substrate. Rifampin (inducer of CYP3A4) and ketoconazole (inhibitor of CYP3A4) serve as positive controls respectively. see catalog listing

Metabolite Profiling

Using LCMS

Metabolite profile comparison allows the selection of the most relevant animal species for drug properties related to human drug metabolism (e.g. safety studies). The animal species that produce a metabolite profile similar to human would be considered a relevant animal species. The use of liver microsomes allows the evaluation of metabolites formed by phase I oxidation (mainly P450 oxidation). The use of hepatocytes allows the evaluation of metabolites formed by all hepatic drug metabolizing enzyme pathways, including both phase I and phase II pathways.

Also see:

In Vitro Toxicity Screening Services

Gene Expression Services