Implementation of Water-Activity Testing to Replace Karl Fischer Water Testing for Solid Oral-Dosage Forms
February 02, 2007
For solid oral-dosage forms, water testing usually is performed to control the chemical, physical, or microbiological properties of the drug product. Measurements of total water as made with Karl Fischer (KF) techniques is not needed and water-activity often will provide a better correlation with changes in chemical, physical, or microbiological properties than KF techniques. In these cases, water activity testing can easily replace KF testing. Water-activity measurements are nondestructive, require little labor, and the equipment required is generally inexpensive. Only a few simple checks are needed to ensure the validity of measurements. Strategies for implementing water activity testing are described.