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A novel type of pH-sensitive hydrogel blend of poly(vinyl alcohol) with acrylic acid-graft-guar gum has been prepared. Microspheres with a size of ∼10 µm were produced by the water-in-oil (w/o) emulsification method for investigating the controlled release of an antituberculosis drug, isoniazid. These novel carriers were analyzed for surface morphology, size, effect of pH, swelling, drug loading, and in vitro release of isoniazid in pH 1.2 and 7.4 media. The kinetics of drug release was analyzed using empirical equations. Release times of the drug were increased to 8 h from its nascent plasma half-life of 0.5-1.6 h.

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Acrylamide-grafted-guar gum (pAAm-g-GG) was prepared and blended with chitosan (CS) to form interpenetrating polymer network (IPN) hydrogel microspheres by the emulsion cross-linking method using glutaraldehyde (GA) as a cross-linker. The microspheres encapsulated up to 74% of ciprofloxacin (CFX), an antibiotic drug, having a plasma half-life of 4 h and the release of CFX was extended up to 12 h. Scanning electron microscopy (SEM) confirmed their spherical structure with smooth surfaces; Fourier transform infrared spectroscopy (FTIR) confirmed the grafting reaction as well as chemical stability of CFX in the blend IPN hydrogel microspheres. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques confirmed the molecular level dispersion of CFX in the matrix. Swelling of microspheres performed in pH 7.4 buffer media was used to understand the drug release kinetics. In vitro release of CFX in pH 1.2 and 7.4 media showed a dependence on blend composition of the IPN, extent of cross-linking as well as initial drug loading. In vitro release data was analyzed using empirical equations, namely, KorsmeyerÀPeppas, to compute the diffusion exponent (n), whose value ranged between 0.19 and 0.33, indicating non-Fickian transport of CFX through the blend IPN hydrogel microspheres.