Screening Study

Exploration for Seeds, and Optimization of Lead Compound

We support studies on pharmacokinetics, pharmacological, physical properties, and safety, at the drug discovery stage in the development process of a new drug.

in vivo study (PK screening)

We perform preliminary examinations of the absorption and main excretion route in animals (rat, dog, monkey, etc.) following the administration of a lead compound.

in vitro study

We evaluate compounds at the drug discovery stage through in vitro studies.

  1. 1.Drug absorption (membrane permeability study using Caco-2 or MDCK cells)

    Membrane permeability is studied using Caco-2 cell (derived from human colon cancer) or MDCK (derived from canine kidney) to predict small intestine permeability in humans.

  2. 2.Metabolic stability

    Metabolic clearance is predicted in vitro based on the metabolic rate of a candidate compound in liver microsomes derived from humans or other animal species. Lead compound is quantitatively determined with LC/MS/MS or HPLC following incubation with microsomes. Then, metabolic activity is calculated based on the decrease of unchanged compound.

  3. 3.Drug interaction (P450 inhibition screening) (enzyme inhibition screening)

    Drug interaction is evaluated from the effects of a lead compound on a probe substance's metabolism in microsomes from human P450 expression system. CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4 are analyzed using LC/MS/MS.

  4. 4.Protein binding

    The binding rate of a lead compound to humans or animal plasma protein is determined using ultrafiltration, equilibrium dialysis method or ultracentrifugal method.

Determination of drug concentration in biological samples

We determine in a timely manner the drug concentration in samples obtained from animals (plasma, tissue, etc.) at the drug discovery stage, and immediately report to the customer.

Pharmacological screening study (drug effect, secondary pharmacological action)

We offer an exploratory screening package for drug effects, and a secondary pharmacological study package for the prediction of secondary pharmacological actions. We also offer a free-choice package in which measurements are freely selected by a customer, and a custom package in which items are set according to requests.

Physical properties (PAMPA, solubility, LogP)

The physical properties of a test sample (membrane permeability, distribution coefficient and solubility) are evaluated with LC/MS/MS and HPLC.

Reactive metabolites

Reactive metabolites produced in the metabolic process of a candidate compound can cause toxicity. Since it is often difficult to detect such reactive metabolites themselves, we will use LC/MS/MS to detect glutathione adducts of the reactive metabolites, in order to provide data useful to avoid toxicity.
We offer the following 3 study systems that are useful for predicting various hepatotoxicities; the studies include the screening of compounds under investigation and the identification of reactive intermediates for characterization.

  1. 1.Identification of glutathione conjugates

    Glutathione conjugates of reactive intermediates are identified through radioactivity measurement using 3H-glutathione and molecular weight determination with LC/MS/MS. Furthermore, the ratio of the reactive intermediates, their structures, etc. will be determined.

  2. 2. Identification of acylglucuronic conjugates

    The production rate of acylglucuronic conjugates and the ratios of their 1-O-β-glucuronic conjugates to isomers are determined.

  3. 3.KCN trap reaction

    We determine whether the reactive intermediates bind with KCN by means of radioactivity measurements using K14CN.

Covalent binding study

We determine the amount of a labeled compound and its metabolites that covalently bind to protein through an in vitro reaction system with human liver microsomes. Rats are subjected to the induction of liver metabolic enzymes followed by administration of the labeled compound, and then the liver is removed at a specified time. Radioactivity in plasma and the liver is measured to obtain the amount of labeled compound and its metabolites that covalently bind to protein in these biological samples in vitro.

Inhibition of fatty acid metabolism

Fatty acids such as palmitic acid produce ATP following β-oxidation in the mitochondria, but if the metabolic process is inhibited, ATP will not be produced and fatty acids will accumulate in the cell, potentially inducing hepatotoxicity.
We examine the degree of inhibition in fatty acid metabolism by measuring the uptake of labeled fatty acids and a candidate compound by the hepatocyte cell lines (HepG2 and Hepa-GR).