Physical and chemical compatibility
Physical and chemical compatibility for physicochemical properties testing is required to demonstrate the stability of the active substance and preparation in storage for safe and efficacious use of product.
Proposed mixtures plus excipients (e.g., using ASTM standard method E 1518-05) are tested for compatibility. Also, aerosol pack pressure limitations are determined to lie in accordance with storage regulations. Low temperature stability testing ('freeze/thaw' cycles), hydrolysis and phase transformation are also key physicochemical factors to consider.