FORMULATION AND CHARACTERIZATION OF TPP CROSS-LINKED CHITOSAN MICROSPHERES LOADED WITH LORNOXICAM

Abstract

In the present study, tripolyphosphate (TPP) cross-linked chitosan microspheres loaded with lornoxicam were prepared by ionic gelation technique. The effect of formulation and process variables on physicochemical properties of microspheres was investigated. FT-IR, DSC and XRD studies revealed the absence of any chemical interactions between the drug and excipients used. Scanning electron microscope images revealed that the prepared microspheres were discrete, broadly spherical with rough surface characteristics. The size of the microspheres was in the range of 615.32 ± 3.21µm to 855.14 ± 2.83µm which increased with increase in core: coat ratio; reduced when the pH of the TPP medium was changed from its original alkaline to acidic and also with increased extent of cross-linking. Percentage encapsulation efficiency was found to be within 56.33 ± 1.8 to 96.59 ± 3.62 and it was largely dependent on core: coat ratio, pH of the TPP medium and extent of cross-linking. Higher drug release was observed for the microspheres prepared at lower core: coat ratios and also for those prepared at the original pH of dispersion medium. On the other hand, more controlled drug release was observed with the microspheres containing higher polymeric levels prepared in the acidic medium. The drug release was also reduced with higher cross-linking conditions. Non-Fickian diffusion controlled drug release mechanism was observed for all the microspheres except those prepared at higher cross-linking conditions, which exhibited zero order release kinetics. Overall, formulation and process variables have significantly affected the physicochemical properties of the prepared microspheres.

Key words: Lornoxicam; Chitosan; Tripolyphosphate; Ionic gelation; Micropsheres; Charecterization