ADME (Absorption, Distribution, Metabolism and Elimination) and pharmacokinetics (PK) studies are designed to establish the behavior of test materials in biological systems. Biological samples (e.g., plasma, urine, feces, bile, etc.) are collected at designated intervals and the amount of test article is measured in each sample. The behavior of the test material is characterized by the relationships between the amount of test material administered, the amount of test material measured in the various matrices, and the time post administration when the measurements are made. Pacific BioLabs can conduct in vivo ADME and PK studies in a variety of species (e.g., rodents, rabbits, guinea pigs and dogs) and by a variety of routes of administration (e.g., oral, intravenous, intramuscular, topical, etc). Through strategic partnerships with external vendors, measurement of test materials is accomplished by various standard analytical procedures. Analysis of PK results (concentration versus time) is conducted in-house with a validated, commercial pharmacokinetic modeling software program.
ADME studies are facilitated by the use radiolabeled dose material, and Pacific BioLabs can conduct radiolabeled studies with either 3H or 14C. Collection of excreta (urine, feces and carbon dioxide) after administration of radiolabeled dose material allows for a quantitative estimate of the tissue distribution, mass balance and routes of excretion for all test material-derived radioactivity.
Purpose of ADME and PK Studies
ADME and PK studies provide a way to evaluate the bioavailability, tissue distribution, active metabolite formation, and elimination of test materials. PK studies may be conducted early in the life cycle of drug development for comparison of new drug candidates with preferred characteristics for subsequent development, e.g., better bioavailability, longer half-life, etc. In addition, PK studies may be conducted late in the drug development cycle, when experiments designed to define optimal drug formulations are conducted.
ADME studies are required for the development of new drugs as they directly relate to the evaluation of human safety, including the validation of the choice of toxicology species based on exposures of the parent compound and its metabolites in animals and humans. ADME studies in nonclinical models are also required prior to conduct of human radiolabel studies. Additionally, these studies may be required by regulatory agencies such as the US EPA for pesticide evaluation.
Learn more about the drug development process.
Download a printable version of our booklet Preclinical Toxicology – Points to Consider in Program Design (PDF).