1. INTRODUCTION

Biological assays, or bioassays, use living material to measure the potency or effect of a pharmaceutical product on a biological system. The living material may be animals, cells, or biomolecules (e.g., peptides, enzymes, antibodies). These assays typically compare Test samples to Standard samples. These comparisons may generate qualitative and/or quantitative data to evaluate the identity or potency of the product. While bioassays are used in many contexts for a broad range of purposes, including characterization, release, stability, and in-process controls, this chapter (as with other USP chapters on bioassays) will focus primarily on their use for quality control (QC) lot release of biological products.