Development of Directly Compressible Ascorbic Acid Tablet Using Novel Excipients

Abstract

Ascorbic acid is a high dose drug, degrading in presence of moisture because of an oxidative process leading to biologically inactive substances. Physical properties of ascorbic acid indicate that it is unsuitable for direct compression at concentrations above 60% in a tabletting mixture. Pharmaceutical excipients contribute unique functionalities to tablet formulations thereby largely determining their quality, compressibility and ease of processing. The objective of the study was to evaluate and compare performance of directly compressible excipient blends for their suitability in ascorbic acid tablet manufacture and to investigate effect of compression pressure on tablet characteristics and assess lubricant sensitivity of compressible excipients and modified hydrogenated fat bleds. These excipients blends were evaluated for particle size, shape, flow properties, % compressibility, Hausner's ratio and elastic recovery. Tablets comprising of drug: excipients (70:30) ratios were compressed using single stroke tablet compression machine. Comparative evaluation of excipients was carried out by investigating effect of compression pressure on hardness and disintegration time of tablets. Lubricant concentration and critical mixing time were optimized using 32 factorial designs. Friedman's test was applied for statistical analysis of experimental data thus selection of suitable excipients. Blends comprising of modified hydrogenated fat, microcrystalline cellulose and aerosil was found to be most suitable combination. Hard, fast disintegrating and stable tablets containing 70% of ascorbic acid with excipients blends were obtained having Friedman's test score of 64.5. Using functionality related testing performance, criteria for selection of directly compressible excipients was developed to facilitate industrial scale-up operations.