DMPK

Studies determining Absorption, Distribution, Metabolism and Excretion (ADME) patterns in laboratory animals and humans are an integral part of the Drug Metabolism and Pharmacokinetics (DMPK) services provided by QPS. These studies are employed at the discovery, candidate selection, Investigational New Drug (IND) enabling and New Drug Application (NDA) stages of a development program.

Many New Chemical Entities (NCEs) can be rapidly screened using the discovery Pharmacokinetics (PK) approach, resulting in more efficient identification of candidates with the most desired ADME properties. By optimizing the lead structures during the candidate selection process, QPS helps to select drug candidates with the best chance of success. Completion of the preclinical DMPK and clinical PK studies will provide an ADME data package that will fully support regulatory IND and NDA submission.

In addition to conducting animal PK studies, QPS performs a comprehensive series of biotransformation and Quantitative Whole-Body Autoradiography (QWBA) studies.

Download

DMPK Leadership Team

Zamas Lam
Zamas Lam
Senior Vice President & Global Head of Pre-Clinical Development
Helen Shen
Helen Shen
Executive Director & Head of DMPK
Shiloh Barfield
Shiloh Barfield
Vice President of Technical Sales, DMPK Hepatic Biosciences
Gavin Shiau
Gavin Shiau
Manager of DMPK and Analytical Chemistry
Gavin Shiau
Ronald M. Laethem
Associate Director, In vitro DMPK
Abu Sadeque
Abu J.M. Sadeque
Director of DMPK

DISCOVERY SCREENING

QPS offers discovery screening as part of the drug candidate selection process. Discovery screen studies require small amounts of compound and data generated in a timely manner (7 days) enabling feedback to the discovery chemist on structural activity relationships. A typical discovery screen may include:

Metabolic Stability
  • Utilizing rat and/or human liver microsomes or hepatocy
  • tesIdentify metabolic “hot” spot
  • Estimate half-life and intrinsic clearance
Plasma protein binding in rodent and/or human
  • Utilizing ultrafiltration or equilibrium dialysis
  • Estimate the extent of binding to plasma proteins
In vitro cytochrome P450 (CYP450) inhibition in human liver microsomes (% inhibition at a single concentration)
  • Utilizing isoform selective probe substrates to assess inhibi tion potential of lead structure(s) to inhibit activity of human CYPs
Rodent pharmacokinetics in N-in-1 or discrete format
  • Single IV or PO dose allows chemical leads to be rank-ordere to optimize PK properties
Preliminary assessment of formulations
  • Single oral dose of compound formulated in pharmaceutically acceptable vehiclesHelps eliminate chemical structures that may be difficult to formulate for oral dosage form

BIOTRANSFORMATION

QPS provides biotransformation studies to determine how a substance may be altered by the action of enzymes. Among QPS studies to support discovery and development of new drug candidates are these:

  • In vitro metabolic stability in hepatic subcellular fractions to determine intrinsic clearance
  • In vitro comparison of metabolite formation in animal and human hepatic preparations, using non-labeled and radio-labeled test articles
  • In vivo metabolite profiling, identification and quantification using samples collected from PK, mass balance excretion studies, and human AME studies to satisfy Metabolites In Safety Testing (MIST) requirement
  • In vitro protein covalent binding assessment using animal and/or human liver microsomes or hepatocytes and in vivo assessment using plasma and liver collected from animals treated with radiolabeled test articles
  • In vitro reaction phenotyping using both recombinant CYPs or UGTs or other enzyme systems and human liver microsomes and chemical inhibitors using non-labeled and radio-labeled test articles

DRUG INTERACTION

QPS provides drug interaction studies to determine the potential of a substance to alter cytochrome P450 activity. Studies conducted to assess inhibition and induction potential to support discovery and development of new drug candidates are:

  • In vitro inhibition characterization in human liver microsomes or hepatocytes to determine reversible or time dependent IC50
  • In vitro mechanistic characterization of reversible inhibitory rate constants, K i
  • Identify the reversible mechanism of inhibition as competitive, non competitive or uncompetitive
  • In vitro mechanistic characterization of time dependent inhibition, K inact and K I
  • Identify the mechanism of time dependent inhibition as metabolite mediated via covalent modification or due to tight binding effect of substrate
  • In vitro characterization of CYP1A2, CYP2B6, and CYP3A4 induction potential in human hepatocytes based on mRNA and/or CYP activity using isoform selective probe substrates

AUTORADIOGRAPHY

Tissue Distribution and Autoradiography

An autoradiograph is an image produced by the radiation emitted from a specimen, such as a section of tissue, that has been treated or injected with a radiolabeled isotope or that has absorbed or ingested such an isotope. QPS performs GLP and non-GLP small and large-animal tissue distribution studies using autoradiography to support drug development and new drug applications.

Full ranges of autoradiography capabilities are available:
  • Quantitative and qualitative whole body tissue distribution studies
  • Predictions of human radioactive dosimetry for clinical radiolabeled mass balance studies
  • Qualitative micro-autoradiography coupled with quantitative autoradioluminography
Tissue Distribution and Quantitative Whole-Body Autoradiography (QWBA)

QWBA offers unique insights for investigators by answering key questions related to tissue pharmacokinetics and metabolism, pathology, toxicology, drug delivery and disposition. QWBA studies provide the tissue distribution and pharmacokinetics data required for new drug registration and for predicting human exposure to radioactivity during clinical radiolabeled mass balance studies.

Tissue Distribution and Micro-Autoradiography (MARG)

Micro-autoradiography is a useful tool for visualizing the location of radiolabeled material at the cellular level.

The following are representative QWBA images from studies conducted at QPS:
WBA_Image_1
WBA_Image_2

Figure 1 & 2: Whole-body Autoradioluminographs of an pregnant rat (day 17) (upper image) and a 17-day old fetus (lower image) showing differential distribution of 14C-AZT-derived radioactivity in liver and brain.

WBA_Image_3

Figure 3: Distribution of 14C-AZT in rat brain Choroid plexus

CANDIDATE SELECTION

To optimize the “drugability” of a small number of drug candidates, a series of ADME studies may be conducted during the candidate selection process to identify the NCE with the best chance of success. A typical data package to support nomination of a NCE from discovery to development status may include the following studies:

Single IV and oral dose in rodent and non-rodent species to determine the pharmacokinetics and oral bioavailability of the drug candidate
  • Administer a pharmacologically active dose to establish the systemic exposure required for biological activity
  • Determine Cmax , Tmax , AUC, t½ , CL, Vd and oral bioavailability
  • Select the candidate with the best pharmacokinetic properties
Plasma protein binding in rodent, non-rodent and human
  • Use ultrafiltration or equilibrium dialysis
  • Determine the extent of binding to plasma proteins
  • Select the candidate with the highest free fraction
In vitro inhibition of CYP in human liver microsomes (determine IC50)
  • Utilizing isoform selective probe substrates to assess inhibition potential of lead structure(s) to inhibit activity of human CYPs (reversible and time dependent)
  • Rank order of lead compounds based on potential to inhibit the CYPs
  • Select the candidate with the lowest potential to cause metabolism-based clinical drug-drug interactions and devoid of time dependent inhibition
Preliminary in vitro metabolism studies to assess potential active metabolites
  • Use human and animal preparations (microsomes, hepatocytes, etc.) to determine major in vitro metabolites
  • Identity structure of major metabolites and determine their biological activity
Determine efflux activity (P-glycoprotein and Breast Cancer Resistance Protein) for CNS programs only
  • Use MDCK-MDR1 and MDCK-BCRP cell lines to assess asymmetrical transport
  • Minimize efflux activity for greater CNS penetration
Temporal relationship between biological activity and plasma concentration
  • Administer lead compounds to animal efficacy models to establish that biological activity is correlated to plasma levels
  • Minimize the selection of lead compounds with active metabolites
  • Eliminate the nomination of pro-drugs
Optimization of oral formulation
  • Select the candidate with the best combination of biological activity, pharmacokinetic properties and ease of formulation for solid dosage form
Toxicokinetics
  • Determine the systemic exposure of lead compounds as part of single-dose and dose-ranging toxicology studies
  • Determine therapeutic index of the lead compound by calculating the ratio of the concentration at the “no observed adverse effect level” dose and the concentration after an active pharmacological dose

Completion of the candidate selection studies will provide the data to support the nomination to development status of the best compound within a list of potential candidates. Depending on the rigor of study designs and appropriateness of the data, most, if not all, of the data package can be included as part of an IND submission.

IND-ENABLING ADME STUDIES

Before a new drug candidate can be administered to humans, a series of preclinical studies must be conducted to characterize the compound. Investigational New Drug (IND) enabling studies are integral to the IND package and must be included in the submission.

Key components of the data package include pharmacology, toxicology and safety pharmacology, ADME and CMC sections of the submission. QPS's comprehensive preclinical capabilities allow completion of all ADME studies necessary to support an IND filing. A typical IND enabling ADME package contains data from the following studies. In general, most ADME data is available at the candidate selection stage:

  • Bioanalytical method validation in one rodent and one or more non-rodent species
  • Single- and multiple-dose pharmacokinetics, dose proportionality and absolute bioavailability in one rodent and one or more non-rodent species
  • Plasma protein binding tests in one rodent, one or more non-rodent species and in human
  • In vitro CYP450 inhibition (1A2, 2B6, 2C8, 2C9, 2C19, 2D6, 3A4/5) in human liver microsomes
  • In vitro metabolism in animal and human hepatic preparations
  • In vivo metabolism profiling and identification from the tox species

Reaction phenotyping in recombinant CYPs or UGTs or other enzyme systems and human liver microsomes with chemical inhibitors

Some pharmaceutical and biotech companies also include the following preclinical studies in their IND enabling package. Although these studies are not required for submission, their inclusion can make the submission package more compelling to move a compound into Phase I clinical studies:

  • Mass balance and routes of excretion in rodents, including biliary excretion in rats
  • Metabolite profiling and identification in rodents and non-rodents
  • Tissue distribution by Quantitative Whole-Body Autoradiography (QWBA)
  • Contribution of P-glycoprotein (P-gp) and breast cancer resistant protein (BCRP) in limiting drug absorption or flux across the blood brain barrier
  • Protein, biochemical and toxicogenomic marker studies for translational medicine, as part of surrogate end-points

Once a compound is moved into the clinical phase, QPS continues to support ADME studies such as ex vivo protein binding determination, metabolite identification and quantification in clinical study samples, characterization of organ specific transporter(s) contribution based on major clearance route and examination of in vitro transporter-drug interactions, determination of IC 50 for Pgp, BCRP, OATP1B1, OATP1B3, OAT1, OAT3, and OCT2.

top
20 years in pharma R&D navigation