Development of the films as tablet degradation indicator

Abstract

The experiment aimed to design thin film as drug degradation indicator to be placed on the surface of tablets. The approach was to prepare thin films in three layers by using hydroxypropyl methylcellulose as film base. The first layer contained red cabbage extract as a source of pH indicator (anthocyanin). The middle layer contained poly-Nisopropylacrylamide (PNIAAm) acting as thermo sensitive polymeric barrier. The last layer was alkaline layer. The thin film was produced and evaluated at 60ºC, 20%RH as a function of time. The result showed that the contraction of PNIAAm after exposure to high temperature effects the release rate of red cabbage extract through thin film. The plot between red color parameter, a* value and time was used to compare the difference of each thin film formulation. ANOVA and Model Independent Methods (difference factor (f1) and similarity factor (f2)) were used to evaluate the profiles of a*value before reaching the end point. Thin films were further formulated and used as tablet degradation detector of two model drugs, glibenclamide and aspirin. Glibenclamide was characterized for solid state transformation and its effect on solubility. Aspirin was evaluated for the rate of chemical degradation to salicylic acid. The solubility of amorphous glibenclamide was decreased below 0.06 mg/ml after storage at 60ºC, 20%RH for 14 days. While aspirin commercial tablets increased the degradation product (salicylic acid) reaching the limit of 0.3% by weight at 60 ºC, 75%RH after 18 days. The color change in thin film correlated well with the degradation rate of glibenclamide and aspirin tablets and was able to visually observe the change. The results indicated that this indicator system can be tailor-made to produce thin film suited for other drugs in detecting degradation which is due mainly to temperature.