Case studies with new excipients: development, implementation and regulatory approval

The purpose of this article is to describe the process whereby new excipients become accepted and to describe three case studies to illustrate the process. New excipients are defined according to the 2005 FDA Guidance on Nonclinical Safety Evaluation of New Excipients. The requirements for safety data submission for new excipients used in different classes of products for different durations are outlined in the guidance. Currently, the development of new excipients is linked to the development and approval of new drug products that contain them. New excipients that are used in US-approved drug products become listed in the FDA Inactive Ingredients Guide (IIG) database. Thereafter, US Pharmacopeia monographs for the new excipients are proposed. New excipients are reviewed and become accepted in the same way in Europe and Japan, except that there is no equivalent IIG database. Therefore, the focus of this article will be on the FDA review process. Three case studies, polyoxyl 15 hydroxystearate, sulfobutyl ether cyclodextrin and silicified microcrystalline cellulose, are used to illustrate how new excipients are accepted and implemented.