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 24h. 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 5h and 96.90 ± 0.66%, 85.05 ± 1.01% and 80.22 ± 0.35%, respectively, in 24h. 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.