Identification and Quantification of Drugs, Metabolites, Drug Metabolizing Enzymes, and Transporters

Concepts, Methods and Translational Sciences

Shuguang Ma, Swapan Chowdhury

• Publisher: Elsevier Science
• Year: 2020
• ISBN:
  9780128200193
• Edition: 2
• Topic: Physical Sciences
• Subtopic: Analytic Chemistry

Identification and Quantification of Drugs, Metabolites, Drug Metabolizing Enzymes, and Transporters, Second Edition, is completely updated to provide an overview of the last decade's numerous advances in analytical technologies for detection and quantification of drugs, metabolites, and biomarkers. This new edition goes beyond LC-MS and features all-new chapters on how to evaluate drug absorption, distribution, metabolism, and excretion, potential for hepatic and renal toxicity, immunogenicity of biotherapeutics and translational tools for predicting human dosage, safety and efficacy of small molecules and biologics. This book will be an important handbook and desk reference for pharmacologists, toxicologists, clinical scientists, and students interested in the fields of pharmacology, biochemistry, and drug metabolism.

• Four sections in the book with 24 chapters give readers an overview of state-of-the-art techniques for identifying and quantifying drugs, metabolites and biomarkers, including a chapter on new approaches for quantification of enzymes and transporters in different tissues
• Focuses on the role of drug metabolism enzymes, transporters in disposition and drug-drug interactions, as well as strategies for evaluating drug metabolism and safety using advanced liver and kidney models. Discussions on immunogenicity risks of biologics and their evaluation methods have been included
• Includes several chapters on advanced translational sciences to predict human dosage, pharmacokinetics and efficacy for small molecules and biotherapeutics
• All chapters are written by experts with a wide range of practical experience from the industry and academia

Part I

Techniques for identifying and quantifying drugs and metabolites

Chapter 1

Bioanalysis of small and large molecule drugs, metabolites, and biomarkers by LC-MS

Naidong Weng; Shefali Patel; Wenying Jian DMPK, Janssen R&D, Spring House, PA, United States

Abstract

Bioanalysis plays an important role in drug discovery and development. Bioanalytical scientists use sound scientific judgment, regulatory compliance, and project management to deliver pivotal data for project decisions in a timely manner. In this book chapter, we highlight the bioanalysis of small and large molecule drugs, metabolites, and biomarkers by LC-MS. We illustrate some of the challenges and problem-solving case examples. The case studies and literature are no doubt incomplete and biased toward our own experiences and publications. Nevertheless, we hope the readers can appreciate the complexity and dynamics of modern LC-MS-based bioanalysis.

Keywords

Bioanalysis; LC-MS; Drugs; Metabolites; Biomarkers; Proteins; Peptides

1 Introduction

Bioanalysis, often shortened to BA, is a subdiscipline within pharmaceutical research and development (R&D). Contemporary bioanalysis quantitatively analyzes very low quantity but highly variable levels (pg/mL-μg/mL) of drug candidates, their metabolites, endogenous biomarkers, etc. in extremely complicated biological matrices such as plasma, blood, urine, and tissues which are harvested from different types of animal species (rodents, dogs, nonhuman primates, etc.) and humans [1]. Bioanalysis supports discovery, nonclinical (tox), and clinical studies (Fig. 1). Fig. 1 shows typical studies an integrated bioanalytical function would support.

Fig. 1 Exemplary bioanalytical support in drug discovery and development. TOX, toxicology; SAD, single ascending dose study; MAD, multiple ascending dose study; ADME, absorption, distribution, metabolism, and elimination; IV, intravenous.

Bioanalytical data are used for calculating pharmacokinetic parameters such as bioavailability, bioequivalence, drug and metabolites exposure, clearance, their distribution into various body organs, correlation of pharmacokinetics (PK) effects and pharmacodynamics (PD) changes, etc. Thus, bioanalysis plays a pivotal role in moving drug candidates from early discovery all the way to regulatory filing and postmarket surveillance in the entire drug discovery and development process. In today's dynamic drug discovery and development environment, bioanalytical scientists not only provide pivotal data but also actively engage in project/program go/no-go discussions, along with colleagues from other functional areas. While the most essential element of bioanalysis is to use analytical chemistry knowledge and state-of-the-art instruments to provide reliable and accurate measurement, knowledge from relevant disciplines such as biotransformation, pharmacokinetics, biology, pharmacology, etc. is invaluable for ensuring appropriate conduct of bioanalysis.

In this book chapter, we try to provide a brief overview of contemporary bioanalysis using the LC-MS platform. It is an impossible task to provide a detailed and comprehensive review of LC-MS bioanalysis in a book chapter. The case studies and literature are no doubt incomplete and biased toward our own experiences and publications. Interested readers are referred to the excellent bioanalysis handbook by Li et al. for a more comprehensive overview of this discipline [1]. Nevertheless, we hope the readers can appreciate the complexity and dynamics of modern LC-MS-based bioanalysis for small and large molecule drugs, metabolites, and biomarkers.

2 Complexity of contemporary bioanalysis

Bioanalytical support is required for important decision-making for all types of studies, from discovery (non-GLP), to development (GLP), and to clinical (GCP) studies. Yet there are many unique and complicated attributes of cost, quality, and timely delivery at each of the abovementioned stages (or substage within each stage). For bioanalysis, the quality and integrity of the bioanalytical data are ultimately the most important attributes. The right scientific and compliance vigor must be applied to each study. The current regulatory landscape for regulated bioanalysis is highly complicated, with guidance from multiple regional health authorities [2–6]. Since guidance from different regions are not totally harmonized, and compounded by individual interpretation of different inspectors, it is still quite a challenge to fully understand and execute the right level of compliance that can be acceptable in the global filing. Efforts are currently being made to harmonize the guidelines into one single global guideline ICH-M10 [7].

While timely delivery of bioanalytical data to support project decisions is a must-do item to meet the ever-tightening drug discovery and development timelines, cost is another attribute that should not be overlooked. The cost of bioanalysis activities should be carefully managed to ensure that it stays within the predetermined budget. On the other side, the application of a tiered approach, which typically consists of three tiers of assay qualification—screening assay, qualified assay, and validated assay with the increased levels of validation parameters—can be used with a balance of scientific vigor and cost [8]. The European Bioanalytical Forum (EBF) recommends exercising this approach for “nonregulated” nonclinical bioanalysis in drug development and using “fit-for-purpose” elements in metabolite quantitation for establishing safety coverage (MIST); urine bioanalysis; and tissue bioanalysis [9, 10]. Of course, the actual implementation of which tier to use depends on each individual study. For example, for urine bioanalysis, while a qualified assay could be used for most clinical studies for understanding the urinary excretion of a drug candidate, validated assays should be applied if renal clearance is the main route of elimination (PK end point) and/or the drug target action is at the kidney.

There is an expansion of bioanalysis scope over the past decades. In the early days, bioanalysis focused on supporting small molecule PK and bioequivalence (BE) from standard formulations such as tablets and capsules. Analysis of metabolites and biomarkers rarely occurred. Currently, PK and BE for both small and large molecules, as well as many hybrid forms of large and small molecules such as antibody drug conjugate (ADC), are supported by bioanalysis [11, 12]. Even for small molecules, advanc...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributors
• Foreword
• Preface
• Part I: Techniques for identifying and quantifying drugs and metabolites
• Part II: Drug metabolism enzymes, transporters and drug-drug interaction
• Part III: Strategy related to drug metabolism and safety
• Part IV: Translational sciences
• Index