Derivatisation of Cashew Gum via Cross-linking with Citric Acid: Characterisation and Preliminary Evaluation of Tableting Properties

A polycarboxylic acid, citric acid, was used to derivatise cashew gum via cross-linking. A dispersion of the purified gum, the acid and sodium dihydrogen phosphate was made in deionised water and concentrated by heating at 40ºC for 18 h. The resulting solid mass was heated at 140ºC for 30 min for the cross-linking. The cross-linking was demonstrated using DSC and FT-IR, and the derivative was characterized by determination of the solubility, water content, swelling and water holding capacity, moisture sorption and desorption, particle flow properties and preliminary studies on drug release in tableting. The results obtained indicated that the cross-linked product differed from the parent gum. At 10 %w/w it retarded drug release while at 3 %w/w it enhanced drug release. The activity of the cross-linked gum in tableting is concentration dependent but could evidently find use as drug release modifier.