Radiation cross-linked carboxymethyl sago pulp hydrogels loaded with ciprofloxacin: Influence of irradiation on gel fraction, entrapped drug and in vitro release

Abstract

Carboxymethyl sago pulp (CMSP) with 0.4. DS, viscosity 184. dl/g and molecular weight 76,000. g/mol was synthesized from sago waste. 10 and 20% w/v solutions of CMSP were irradiated at 10-30. kGy to form hydrogels and were characterized by % gel fraction (GF). Irradiation of 20% CMSP using 25. kGy has produced stable hydrogels with the highest % GF and hence loaded with ciprofloxacin HCl. Drug-loaded hydrogels were produced by irradiating the mixture of drug and 20% CMSP solution at 25. kGy. After irradiation, the hydrogels were cut into circular discs with a diameter of 6±1. mm and evaluated for physicochemical properties as well as drug release kinetics. The ciprofloxacin loading in the disc was 14.7%±1 w/w with an entrapment efficiency of 73.5% w/w. The low standard deviation of drug-loaded discs indicated uniform thickness (1.5±0.3. mm). The unloaded discs were thinner (1±0.4. mm) and more brittle than the drug-loaded discs. FESEM, FT-IR, XRD, DSC and TGA analysis revealed the absence of polymer-drug interaction and transformation of crystalline to amorphous form of ciprofloxacin in the discs. The disc sustained the drug release in phosphate buffer pH 7.4 over 36. h in a first-order manner. The mechanism of the drug release was found to be swelling controlled diffusion and matrix erosion. The anti-bacterial effect of ciprofloxacin was retained after irradiation and CMSP disc could be a promising device for ocular drug delivery. © 2014 Elsevier Ltd.