Compression coated systems for colonic delivery of 5-fluorouracil.

Compression coating is one of the approaches for delaying the release of drugs. The aim of this study was to develop colon-specific compression coated systems of 5-fluorouracil (5-FU) for the treatment of colorectal cancer using xanthan gum, boswellia gum and hydroxypropyl methylcellulose (HPMC) as the coating materials. Core tablets containing 50 mg of 5-FU were prepared by direct compression. The coating of the core tablets was done using different coat weights (230, 250, 275 and 300 mg) and different ratios (1:2, 2:1, 1:3, 1:7 and 3:4) of boswellia gum and xanthan gum and different ratios (1:1, 1:2, 2:1, and 2:3) of boswellia gum and HPMC. In-vitro release studies were carried out using simulated gastric and intestinal fluids, with and without rat caecal contents. Among the different ratios used for coating with boswellia:xanthan gum combination, ratio 1:3 gave the best release profile with the lowest coating weights of 230 mg (7.47 +/- 1.56% in initial 5 h). Further increase in the coat weights to 250, 275 and 300 mg led to drug release of 5.63 +/- 0.53%, 5.09 +/- 1.56% and 4.57 +/- 0.88%, respectively, in the initial 5 h and 96.90 +/- 0.66%, 85.05 +/- 1.01% and 80.22 +/- 0.35%, respectively, in 24 h. When coating was carried out using different ratios of the combination boswellia gum and HPMC, the ratio 2:3 gave the best results among the initial trial batches (7.80 +/- 0.57% in 5 h). Increasing the coat weights to 250, 275 and 300 mg led to drug release of 6.5 +/- 0.27%, 3.70 +/- 2.3% and 2.99 +/- 0.72%, respectively, in the initial 5 h and 96.90 +/- 0.66%, 85.05 +/- 1.01% and 80.22 +/- 0.35%, respectively, in 24 h. In-vitro studies were further carried out in the presence of 2% w/v rat caecal contents, which led to complete release of the drug from the tablets. Therefore, this study lays a basis for use of compression coating of 5-FU as a tool for delaying the release of the drug, which ensures better clinical management of the disease.