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 (1-15w/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 1as the AMA binder concentration increased from 0.75 to 11.25w/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; 0.75w/w) to 9 min-2 (AMA; 11.25w/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

Relationship between Slugging Pressure and Brittle Fracture Tendency - A Case Study for Aspirin Tablets

OBJECTIVE - Slugging is a pre-compression technique for the dry granulation of hydrolysable drugs (e.g. aspirin). The study was carried out to relate the slugging load to the hardness of the granules and the brittle fracture tendency of the final (recompressed) tablets. METHOD - Varying compression load were applied to aspirin powder to form slugs; which were subsequently broken down to form granules. These were recompressed to give the final tablets. The hardness of the slugs was determined and taken as measure of the hardness of the resulting granules. The following tableting parameters were measured for the final tablets - tensile strength (T); packing fraction (P[f]) and the brittle fracture index (BFI). RESULTS - A high slugging load was associated with the formation of hard slugs and hence hard granules. Upon recompression the hardest granules formed the hardest tablets (T = 3.29MN m**-2) while the softest granules formed the softest tablets (T=1.09MN m**-2). In turn; the hardest tablets displayed the highest brittle fracture tendency (BFI = 0.59) compared with the softest tablets (BFI= 0.21). A positive linear correlation existed between tablet hardness (T) and BFI values (r = 0.98). CONCLUSION - The study showed that excessive slugging load produces hard aspirin granules which in turn yields hard but friable tablets

Short Paper - Effect of Acid Treatment on the Consolidation and Plasto-Elasticity of Tapioca Powder

PURPOSE: The effects of treating the tapioca (the fibrous residue obtained after up to 90 percent of the proportion of starch has been removed from the peeled and rasped roots of cassava tubers powder with dilute solutions of hydrochloric acid) in order to find an approach for rendering an otherwise poorly compressible material to a directly compressible powder. METHOD: The parameters measured were the degree of consolidation of the powder after compression (i.e. the packing fraction of resulting tablets); the plasto-elasticity of the powders as reflected by the brittle fracture index (BFI) of the tablets made from the powders and the viscosities of mucilages derived from the powders. The influence of time of exposure and the concentration of acid used in the treatment were studied. RESULTS: The degree of consolidation of the powder increased slightly with increase in duration of exposure to acid (24 - 72 h) but drastically with increase in the acid concentration from 0.1 to 0.4 mol. L**-1. On the other hand; the plasto-elasticity of the powders as measured by the BFI values and the viscosities of mucilages derived from the powders decreased slightly with duration of exposure but drastically with increase in acid concentration. A change in acid concentration was therefore the more determinant factor with regards to the consolidation and plasto-elasticity properties of the powders. The decrease in the viscosities of the mucilages following acid treatment of the powders was indicative of a breakdown of polymeric structure in the powder CONCLUSION: Acid treatment of tapioca powder imparted plasticity in tapioca powder which became compressible