Methods and Applications of Statistics in Clinical Trials, Volume 1: Concepts, Principles, Trials, and Designs

Chapter 10

Biological Assay, Overview

Pranab K. Sen

10.1 Introduction

This article mainly emphasizes the classical aim of biological assay (or bioassay), to estimate relative potency, arising out of a need for biological standardization of drugs and other products for biological usage. There is a basic difference between biological and chemical endpoints or responses: the former exhibits greater (bio)variability and thereby requires in vivo or in vitro biological assays wherein a standard preparation (or a reference material) is often used to have a meaningful interpretation of relative potency. However, the term bioassay, has also been used in a wider sense, to denote an experiment, with biological units, to detect possible adverse effects such as carcinogenicity or mutagenicity; Mutagenicity Study). In the context of environmental impact on biosystems, toxicodynamic and toxicokinetic (TDTK) models as well as physiologically based pharmacokinetic (PBPK) models have been incorporated to expand the domain of bioassays; structure–activity relationship information (SARI) is often used to consolidate the adoption of bioassays in a more general setup; the genesis of dosimetry (or animal studies) lies in this complex. The use of biomarkers in studying environmental toxic effects on biological systems, as well as in carcinogenicity studies, has enhanced the scope of bioassays to a greater inter-disciplinary field; we need to appraise, as well, bioassays in this broader sense. Further, ...