Formulation and Evaluation of Microspheres as an effective Colon Targeting Drug Delivery System

Abstract

The present work comprised of the preparation of coated HPMC capsules of meloxicam microspheres in order to target the drug release in colon resulting in increased absorption and subsequent bioavailability. The meloxicam microspheres were developed in nineteen different batches using HPMC, combination of EC with HPMC, Eudragits (S100, RS100 and E100) in different drug and polymer ratios by solvent evaporation method. The formulation of different batches were examined by various studies i.e. percentage yield, surface morphology (SEM), particle size analysis, entrapment efficiency, drug compatibility with polymers using FTIR and in-vitro drug release determinations. The complex of meloxicam with β-cyclodextrin increased the solubility of the drug accompanying its in-vitro release. The microspheres filled HPMC capsules were coated with eudragit S100 which proved to be an effective method for drug targeting to the colon. A 22 factorial design showed that a very significant increase in release of the drug using polymers i.e. HPMC, E.C with HPMC, Eudragit S100, Eudragit RS100, Eudragit E100 could be obtained by the exclusive manipulation of two variables i.e. surfactant and polymer concentrations. The drug loaded microspheres showed percentage drug entrapment as 35.09-62.50% in A1-A4, 76.29-87.78% in B1-B4, 81.36-92.70% in S1-S4, 65.47-69.4% in RS1-RS4 and 68.91-78.08% in E1-E3. The pH 7.4 phosphate buffer and simulated colonic fluid were used for the in-vitro release tests. The best drug release profiles were seen with formulations A3, B2, RS1, S1 and E2 (containing different ratios of drug: polymer) coated with 15% (w/v) Eudragit S-100 solution.