Controlled release of amoxicillin from hydroxypropyl cellulose-graft-polyacrylamide / chitosan microspheres

In the thesis study, temperature sensitive chitosan/hydroxypropyl cellulose-graft-polyacrylamide (CS/HPC-g-PAAm) blend microspheres in hydrochloric acid (HCl) catalyst using glutaraldehyde (GA) as crosslinker to provide controlled release of the antibiotic drug amoxicillin trihydrate as a controlled drug release system was prepared by emulsion cross-linking method. In the first step, graft copolymers of hydroxypropyl cellulose (HPC) with acrylamide (AAm) were synthesized using cerium (IV) ammonium nitrate as initiator. Synthesized graft copolymers (HPC-g-PAAm) were characterized using Fourier transform infrared spectroscopy (FTIR), elemental analysis, and differential scanning calorimetry (DSC). The lower critical solution temperatures (LCST) of the synthesized copolymers were determined. Prepared microspheres were characterized by DSC, X-ray diffraction (XRD), and FTIR spectroscopy. In addition, the surfaces of the empty and drug-loaded microspheres were examined by scanning electron microscopy (SEM). The effects of variables such as CS/HPC-g-PAAm ratio, drug/polymer ratio, amount of cross-linker and grafting reaction time on AMX release, in three different temperatures as 25 °C, 37 °C and 50 °C and three different pH environments (1.2, 6.8, and 7.4) were investigated. The release results showed that the microspheres were temperature sensitive and that the microspheres with higher grafting time and hence higher AAm graft yield had more controlled AMX release. The drug release behavior of all microspheres obtained was kinetically investigated in terms of different release mechanisms, and it was seen that the release system followed the Korsmeyer-Peppas equation more than the other equations.