Blend microspheres of chitosan and polyurethane for controlled release of water-soluble antihypertensitive drugs

Blend microspheres of chitosan and polyurethane (PU) have been prepared by water-in-oil emulsion cross-linking method and used to encapsulate two water-soluble and having widely different plasma half-life cardiovascular drugs, viz., isoxsuprine hydrochloride and calcium dobesilate. The blend miscibility of the polymers was confirmed by differential scanning calorimetry at > 60 wt% of PU. The microspheres were characterized by scanning electron microscopy to understand the morphology of the drug-loaded microspheres. Chemical interactions between drug molecules and the carrier polymers have been investigated by Fourier transform spectroscopy. XRD measurements on placebo matrices, drug-loaded formulations and nascent drugs indicated their uniform dispersion in the polymer matrix. In vitro release experiments performed in both acidic pH of 1.2 and alkaline pH of 7.4 increased the release time of both the drugs in the media employed. Kinetics of drug release was analyzed by empirical equation, suggesting the deviation from Fickian transport to non-Fickian trend.