Stability testing of biological drugs should be more comprehensive than that of small molecule compounds. It should cover many more aspects of drug development & manufacturing, including holding time, shipping, freeze/thaw cycles, temperature, exposure to oxygen & light, physical stress, and excipient & container compatibility. Some characterization work should be done early in the development of a drug to identify the degradation pathways so that potential problems associated with stability, storage conditions and formulation design can be avoided during clinical trials. Forced degradation studies exposes a drug substance to harsher conditions than the product would be expected to experience and determining at what point & how it degrades. Some characterization work should be done early in the development of a drug to identify the degradation pathways so that potential problems associated with stability, storage conditions and formulation design can be avoided during clinical trials. A good understanding of product stability early on can help companies make assessments and comparisons on product comparability following manufacturing changes.