IPEC e-newsletter - Excipients Insight April/May 2018 - 15-05-18


Inside this issue


New USP Chapter <922> Water Activity

The US Pharmacopeia has proposed a new General Chapter <922> Water Activity, for suppliers and manufactures of excipients, drug substances, drug products, veterinary products, regulatory agencies, and manufacturers of water activity instruments.

USP’s Physical Analysis Expert Committee says the new chapter is intended to provide guidance for performing measurements of water activity (Aw)". Furthermore, the chapter "will specify methods for qualification of instruments, calibration of instruments, methods for performing water activity measurements, and reporting of results".

It notes that water activity (Aw) is the effective concentration of pure water in a raw material or product. When water is strongly bound to a solute or surface, it does not contribute to the Aw. It has been established that bacterial growth is correlated with water activity, not water content. Substances (e.g. food) obtaining higher Aw values tend to support more microorganisms.

The deadline for input for preparing the draft is 30 April 2018. The final proposal is estimated to be published in Pharmacopeial Forum (PF) 44(6) in November 2018. However, in consultation with our IPEC-Americas colleagues, this outline of a proposed new chapter likely reflects current practices for water activities in pharmaceutical companies.  

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