Larry Callahan

Lead Scientist- Substance Registration System FDA

Dr. Callahan obtained his Ph.D. in Chemistry from the University of Chicago. He was previously employed at FDA, NIH and the United States Pharmacopiea (USP). He has been involved in Nucleic Acid, HIV, tuberculosis research and the development of analytical methods for biotechnology-derived products. He also has been responsible for the management and development of chemical/biological databases for the National Institute of Allergy and Infectious Disease, National Library of Medicine, National Cancer Institute and the Food and Drug Administration.

Dr. Callahan is currently responsible for the development and management of the FDA Global Substance Registration System (G-SRS). The goal of the SRS is to define all substances in FDA regulated products and assign a Unique Ingredient Identifier (UNII) to each substance and create meaningful relationships between substances. These relationships include impurities, metabolites, metabolic enzymes, transporter and target proteins along with specifications for active substances and LADMER data for substances and products. The G-SRS also links substances to products, applications clinical trials and adverse events.

Dr. Callahan and Dr. Frank Switzer were the primary editors of the ISO 11238 Standard for defining substance and with Dr. Herman Diederik of the Dutch Agency and the EMA are the primary editors of ISO TS-19844 document which is the implementation guide for defining all substances in medicinal products. Dr. Callahan is also the FDA lead on the Global Ingredient Archival System (GInAS) project, which attempt to integrate regulatory, toxicological, and clinical information on all substances in medicinal products.