Matrix release from tablets prepared with aqueous dispersion of an acrylate methacrylate (a water - insoluble) copolymer as binder

PURPOSE: To investigate the binder effect of aqueous dispersions of acrylate methacrylates (AMA) copolymer with a view to obtaining matrix (non-disintegrating) tablets with a retard release property. METHODS: Aqueous dispersions of AMA (1-15% w/v) were formed by a coacervation procedure using ethanol (10 ml) as solvent and water (90 ml) as non-solvent for the copolymer. The aqueous dispersions were used to wet–mass the drug (paracetamol) powder. Resulting granules were compressed to 500 mg tablets using a single punch machine. The tablets were subjected to hardness, friability, disintegration and dissolution tests. RESULTS: The granules formed hard tablets (tensile strength 1 - 2.0 MNm-2) with low friability decreasing from 2 to 1 % as the AMA binder concentration increased from 0.75 to 11.25% w/w. The tablets failed to disintegrate in 3 hr. Drug release generally followed the Higuchi square root of time kinetic (R2
0.95). The AMA binder markedly retarded drug release as reflected by the sharp decrease in the dissolution rate constant from 30 min–2 (AMA, 0.75% w/w) to 9 min–2 (AMA, 11.25% w/w). CONCLUSION: The AMA dispersion is an effective binder, producing matrix tablets with a retard release property controlled by the binder content in the tablets. Keywords: Acrylate methacrylate copolymer; Aqueous dispersions; Matrix tablets, Retard release; Friability index; Tensile strength.