Viruses, Serums, Toxins, and Analogous Products; Determination of Moisture Content in Desiccated Biological Products

We are amending the Virus-Serum-Toxin Act regulations for the determination of moisture content in desiccated biological products to require that such determinations be made using a gravimetric method that expresses moisture content as the percentage of weight a product loses during a drying cycle, and to require that the maximum percentage of moisture permitted for a satisfactory test must be specified in a filed Outline of Production. The gravimetric method has been adopted as an international standard by scientific experts and regulatory authorities in the United States, Canada, Japan, and the European Union. In addition, we are amending the regulations pertaining to general requirements for live bacterial vaccines and general requirements for live virus vaccines to specify the gravimetric method when testing for moisture content. These actions will update the regulations by providing a uniform method of determining moisture content in desiccated products and ensure the stability of that product during its dating period.