Development of Controlled Release Microspheres of amoxicillin by using Natural Gums

The present investigation aimed to formulate and evaluate in vitro performances of controlled release amoxicillin microspheres for the potential application in the treatment of gastric and duodenal ulcers, which were associated with Helicobacter pylori. Method: Amoxicillin control release microspheres containing as guar gum and xanthan gum as control release polymer were prepared by an external ionotropic gelation method using sodium alginate and calcium chloride. The prepared microspheres were evaluated for their micromeritic properties, drug content and encapsulation efficiency and characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction and scanning electron microscopy. The in vitro release studies were performed by buffer change method using pH 1.2 buffer and pH 6.8 phosphate buffer. Results: The preliminary trials results indicate that quantity of gelling agent, drug-to-polymers ratio, time for stirring and speed of rotation has impact on the characteristics of microspheres. The prepared microspheres were half white, free flowing, spherical in shape with mean particle size in the range of 450 to 779 µm. The drug-loaded microspheres showed 60.42-89.23% of entrapment and in vitro drug release was extended up to 12 hr releasing 18.9 –93.86 % of the total drug from the microspheres. The optimized formulation batch exhibited high drug entrapment efficiency of 83%, the particle size was 450 µm and a controlled drug release was observed for more than 12 hr. The infrared spectra showed stable character of amoxicillin in the drug-loaded microspheres and revealed the absence of drug-polymer interactions. The morphological characteristics of the microspheres were studied under a scanning electron microscopy revealed that the microspheres were spherical and porous in nature. In vitro release studies showed that amoxicillin released bit slightly faster in pH 1.2 gastric fluid than in pH 7.8 phosphate buffer. The release kinetics was achieved with Koresmeyer-Peppas plot followed by zero order with Fickian diffusion mechanism. Conclusions: The prolonged gastrointestinal residence time and enhanced amoxicillin stability resulting from the amoxicillin microspheres might make a contribution to H. pylori complete eradication