Development of Novel Combined Time and pH-Dependent based Drug Delivery Systems for Targeting 5-Fluorouracil to the Colon

Abstract

The present work is aimed to develop new oral drug delivery systems of 5-fluorouracil for the treatment of colorectal cancer by using hydrophilic swellable polymer hydroxy propyl methyl cellulose (HPMC) and pH responsive soluble polymer Eudragit L100 (ED) as coating materials. Core tablets containing 50mg of 5-fluorouracil were prepared by direct compression. The core tablets compression coated with different ratios (9:1, 8:2, 7:3, 6:4 and 5:5) of HPMC and ED with a coat weight of 300 and 400mg. All the formulations were evaluated for the hardness, friability, drug content uniformity and in vitro drug release studies in media of different pH 1.2, 7.4 and 6.8. The formulations released 0 to 7% of the drug in physiological environment of stomach and small intestine depending upon proportion of HPMC and ED used in the coat. Among the different ratios used for coating with HPMC:ED combination, ratio 9:1 gave the best release profile with the coat weight of 300mg (1.34% in the initial 5h and 87% in 24 h). Further increase in the coat weight to 400mg with different ratios of 9:1, 8:2, 7:3, 6:4 and 5:5 led to drug release of 0%, 0%, 0%, 3.47% and 6.25%, respectively in the initial 5 h and 73.52%, 87.03%, 92.18%, 96.33% and 97.61%, respectively, in 24 h. Thus, based on the results of in vitro drug release studies, the ratio 7:3 with a coat weight of 400mg was found to be suitable for targeting 5-fluorouracil to the colon without being released in physiological environment of stomach and small intestine. The formulation showed no change in physical appearance, drug content or in vitro release pattern after storage at 40° C / 75% RH for 3 months. The release of 5-fluorouracil from developed formulation was directly proportional to amount of ED used in the coat. The DSC and FTIR studies indicated no possibility of interaction between 5-fluorouracil and excipients.