Development of a modified hard gelatin capsule for colon- targeted drug delivery of hydrogel-based piroxicam microparticles

Purpose: To develop modified hard gelatin capsules (MHGCs) for colon-specific delivery of hydrogel-based piroxicam microparticles. Methods: Solvent evaporation technique was adopted for the microencapsulation of piroxicam using liquid paraffin (PL.MPs) and soybean oil (PS.MPs) which were subsequently encapsulated in MHGCs (water-impervious). Anti-inflammatory and in vitro dissolution studies were conducted on the unencapsulated microparticles (MPs). Furthermore, in vitro colon-specific sequential drug release from impervious capsules was carried out for 2 h at pH 1.2 and 3 h in 6.8, and >= 5 h in 7.4, to simulate drug release in the stomach, small intestine, and colon environment, respectively. Differential scanning calorimetry (DSC) analysis was also conducted on the formulations.Results: Edema inhibition of PL.MPs and PS.MPs were within the range of 51.0 - 64.0 and 58.0 - 69.0 %, respectively. In vitro colon-specific drug dissolution studies revealed absence, minimal, and highest amounts of drug release from MHGCs in pH 1.2, 6.8 and 7.4 media, respectively. Decreased crystallinity of the microparticles was indicated by a broad endothermic peak.Conclusion: The MHGCs hold promise as a potential alternative delivery system for hydrogel-based piroxicam microparticles designed for colon-targeted drug delivery. However, clinical development studies are required.