Co-polymerized Gellan Gum: A Carrier for Controlled Drug Delivery

Background: Natural polymers have been explored for drug delivery applications since decades, but limited success has been ascribed to their undesired physicochemical properties. Here, we demonstrate the grafting of an anionic and hydrophilic exopolysaccharide ‘gellan gum’with polyacrylamide using microwave irradiation and its potential in controlled delivery of aceclofenac. Methods: Grafting of gellan gum was optimized w.r.t. microwave temperature, exposure time, concentration of free radical initiator and characterized by FTIR, DSC, XRD and SEM analysis. Subsequently, gellan gum and gellan-g-poly(acrylamide) were formulated into aceclofenac tablets and subjected to in vitro drug release, swelling and stability studies. Results: The microwave temperature, exposure time and concentration of free radical initiator had synergistic effect on grafting efficiency up to 80 °C, 120 s and 5 g, respectively. The swelling studies carried out at different pH conditions support the potential of gellan-g-poly(acrylamide). Gellan gum and gellan-g-poly(acrylamide) formulations were compared with commercialized sustained release Zerodol-CR tablets. In vitro release studies revealed the superiority of gellan- g-poly(acrylamide) which was able to sustain the drug release up to 97% over 24 h by zero order kinetics with n value within the range of 1.38-1.80 indicating super case-II (non-Fickian) transport i.e. dominated by diffusion and erosion from polymeric matrix. Interestingly higher drug release was observed in acidic conditions. Conclusion: These findings validate the crucial role of co-polymerization in improving the efficacy of existing natural polymers and support the competence of gellan-g-poly(acrylamide) in the design of highly efficient controlled drug delivery system.