Stability Study Through Water Activity Measurements for Dispensed Powdered Raw Materials.

This article investigates the use of water activity (aw) measurements as an indicator of microbiological, physicochemical, and organoleptic stability in powdered pharmaceutical raw materials during an 8-day holding time. Five raw materials—clobetasol 17-propionate, atorvastatin calcium, fusidic acid, acetaminophen direct compression, and sildenafil citrate—were stored under conditions aligned with United States Pharmacopeia (USP) monographs, and their water activity was measured using the chilled-mirror dew point method on days 0, 3, and 8. Results showed that water activity remained below 0.60 throughout the holding period, correlating with stable microbiological counts, unchanged organoleptic properties, and consistent chromatographic profiles, indicating no degradation or microbial growth. The study concludes that water activity below 0.60 can reliably indicate the microbiological safety and chemical stability of these pharmaceutical raw materials during storage, supporting its use as a monitoring tool in pharmaceutical stability programs.