The determination of the water activity of nonsterile pharmaceutical dosage forms aids in the decisions relating to the following:

1. optimizing product formulations to improve antimicrobial effectiveness of preservative systems,

2. reducing the degradation of active pharmaceutical ingredients within product formulations susceptible to chemical hydrolysis,

3. reducing the susceptibility of formulations (especially liquids, ointments, lotions, and creams) to microbial contamination, and

4. providing a tool for the rationale for reducing the frequency of microbial limit testing and screening for objectionable microorganisms for product release and stability testing using methods contained in the general test chapter Microbial Enumeration Tests 〈61〉 and Tests for Specified Microorganisms 〈62〉.