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.
Microspheres of poly(vinyl alcohol) (PVA) and hydroxyethyl cellulose (HEC) were prepared as semiinterpenetrating networks (IPNs), crosslinked with glutaraldehyde and used in controlled release of theophylline (THP), an anti-asthmatic drug. Formulations were characterized by X-ray diffraction (XRD) to understand uniform distribution of THP, Fourier transform infrared (FTIR) spectroscopy to understand chemical interactions, universal testing machine (UTM) for mechanical stability, and scanning electron microscopy (SEM) for investigating the morphology of the microspheres produced. SEM indicated smooth surfaces of the microparticles and sizes of around 10-15 lm giving high encapsulation efficiency up to 69%. Equilibrium uptake performed in double distilled water and in vitro release studies performed in 1.2 and 7.4 pH buffer media indicated the effect of extent of crosslinking and HEC content of the semi-IPN matrix on the release of THP that was extended up to 12 h. Analysis of in vitro results using empirical equation suggested a deviation from the Fickian transport. Drug diffusion was estimated from the Fick's diffusion equation for spherical geometry. Kinetics of drug release followed the Higuchi square root equation, indicating that release is diffusion-controlled.
Carboxymethyl guar gum (CMGG), an anionic semisynthetic GG derivative, was synthesized by incorporating CM group into GG chain. Microspheres were prepared by loading abacavir sulfate (AS) using water-in-oil (w/o) emulsion method. Formulations were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), X-ray diffraction (XRD), thermogravimetry (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). In vitro release profiles of GG and CMGG loaded with AS performed in pH 1.2 as well as 7.4 buffer media at 37 C displayed the varying drug release profiles in stomach and intestinal conditions. Release of the drug was extended up to 28 h in both GG and CMGG matrices, but the burst release observed in case of GG matrix was reduced in the case of CMGG. The kinetics of in vitro release was analyzed using the empirical equations.
A novel drug delivery system using semi-interpenetrating (semi-IPN) microspheres of dextran-grafted-acrylamide (Dex-g-AAm) and poly(vinyl alcohol) (PVA) was prepared in the size range of 80–100 μm by emulsion cross-linking for investigating controlled release (CR) of an anti-HIV agent, abacavir sulfate. The graft copolymer was confirmed by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The microspheres were characterized for morphology, swelling, and in vitro release of abacavir sulfate in pH 1.2 and 7.4 buffer media to display the effect of drug release in acidic and alkaline conditions. The kinetics of in vitro release was analyzed using the empirical equations to understand the nature of release mechanism.
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