5-fluorouracil loaded guar gum microspheres for colon delivery: preparation, characterization and in vitro release.

The present investigation is aimed to develop a new formulation containing chemically crosslinked guar gum microspheres loaded with 5-fluorouracil for targeting colorectal cancer. The emulsification polymerization method involving the dispersion of aqueous phase of guar gum in castor oil was used to prepare spherical microspheres. Various processing parameters were studied in order to optimize the formulation. Particle size and surface morphology of the microspheres were determined using optical microscopy and scanning electron microscopy. The in vitro drug release studies performed in simulated gastric fluid (SGF) for 2 h followed by intestinal fluid for 3 h, revealed the retention of the drug inside the microspheres from which only (15.27 +/- 0.56) % of the drug was released in 5 h. In vitro release rate studies were also carried out in simulated colonic fluid (SCF) in the presence of rat caecal contents, which showed improved drug release. The drug release from the formulation was found to be (41.6 +/- 3.5) % with 2% (w/v) caecal matter in 24 h as compared to control study where (25.2 +/- 3.5) % of drug was released. The drug release from the formulation with 2% and 4% rat caecal contents medium after 2 days of enzyme induction was found to be (56.3 +/- 4.1) % and (78.9 +/- 2.8) % in 24 h respectively. Similarly, (61.3 +/- 5.4) % and (90.2 +/- 2.9) % drug was released respectively with 2% and 4% rat caecal matter after 4 days of enzyme induction and (72.1 +/- 2.9) % and (90.2 +/- 3.2) % after 6 days of enzyme induction. In this way, 5-fluorouracil loaded guar gum microspheres have shown promising results in the management of colorectal cancer, warranting thorough in vivo study for scale up technology.