Abstract

The purpose of the present investigation was to achieve colon specific delivery of sennosides using the polysaccharide pectin as a compression-coating agent. In this study, pectin along with hydroxypropylmethylcellulose was used for compression coating of the core tablets of calcium sennoside. Drug dissolution and erosion studies were carried out in pH 1.2 and phosphate buffer pH 7.4 using a pectinolytic enzyme. The system was designed based on the gastrointestinal transit time concept, assuming colon arrival time to be 6 h. It was found that pectin alone was not sufficient to protect the core tablets during entire gastrointestinal transit time. Addition of hydroxypropylmethylcellulose was required to control the erosion of tablets. In this investigation a 3 ² factorial design was constructed to investigate the influence of two variables; the amount of hydroxypropylmethylcellulose (X1) and coat weight of the tablets (X2) on the time taken for 50% erosion of tablet in presence of pectinase enzyme (TE ₅₀ ) and average percent weight difference between tablets with and without enzyme at the 10 th hour (% WD). The results revealed that for protecting the calcium sennosides core tablets in upper gastrointestinal tract, the core tablets should be coated with lower amount of hydroxypropylmethylcellulose and higher amount of coat weight. The main effects were found to be statistically significant in nature. The amount of hydroxypropylmethylcellulose exhibited predominant action as compared to coat weight. In vivo performance was assessed by X-ray roentegenography study. The pectin-hydroxypropylmethylcellulose coating was found to be a promising colon delivery system for those drugs like sennosides.