Quaternary polymethacrylate−magnesium aluminum silicate film formers: Stability studies for tablet coatings

The objective of this work was to investigate the long-term stability of quaternary polymethacrylate-magnesium aluminum silicate (QPM-MAS) nanocomposite film-coated tablets compared to that of QPM-coated tablets. QPM- and QPM-MAS-coated tablets prepared without or with a curing process at 60 °C for 12 h were stored without packaging under ambient (26 ± 2 °C, 50% relative humidity (RH)) and accelerated (45 ± 1 °C, 75% RH) conditions. The outer morphology, water uptake and drug release parameters (lag time and drug release rate) were investigated. The results showed that the QPM-coated tablets prepared without or with curing (60 °C for 12 h) presented darker brown and shinier films, whereas the QPM-MAS 4:0.75-coated tablets showed minor change in color and appearance after storage under both conditions for 4 months. The QPM- and QPM-MAS-coated tablets experienced a decrease in % change in wet mass and drug release rate, and an extension in lag time when stored under both conditions. Changes in the water uptake and drug release of the coated tablets were also observed when a curing process was involved. This finding suggested that temperature and humidity strongly influenced further fusion of the QPM particles, even though MAS could interact with QPM to form nanocomposites in the coated films. Therefore, temperature control and water vapor-resistant packaging are necessary for maintaining the long-term stability of the QPM and QPM-MAS film-coated formulations.