PREPARATION AND CHARACTERIZATION OF AMPICILLIN LOADED METHYLPYRROLIDINONE CHITOSAN AND CHITOSAN MICROSPHERES

Ampicillin was embedded in microparticles made of a new derivative of chitosan: methylpyrrolidinone chitosan. They were prepared using diffe rent drug-to-polymer weight ratios and by a spray-drying technique. Sp ray-dried drug-loaded chitosan microspheres were prepared for comparis on. The microparticles were characterized by scanning electron microsc opy (SEM), particle size analysis, differential scanning calorimetry ( DSC) and in vitro drug release. Microbiological assay was performed us ing different bacterial strains. Spray-dried microspheres of almost sp herical shape, smooth surface and narrow size distribution were always obtained. Ampicillin loaded into both polymer matrices showed amorpho us behaviour as determined by DSC. Drug-loaded microspheres resulted t o control the drug release in a 30-120 min range, depending on chitosa n type. Thermal denaturation of the microspheres does not modify drug release rate. The results of the microbiological assay show that the l oading of ampicillin into chitosans is able to maintain or improve the anti-bacterial activity of the drug. (C) 1998 Published by Elsevier S cience Ltd. All rights reserved.