PREPARATION, CHARACTERIZATION AND IN-VITRO ANTIMICROBIAL ACTIVITY OF AMPICILLIN-LOADED POLYETHYLCYANOACRYLATE NANOPARTICLES

In this paper, the experimental conditions for preparing ampicillin-lo aded polyethylcyanoacrylate (PECA) nanoparticles are described. The ef fects of drug concentration and surfactant type in the polymerization medium on the particle size distribution and loading capacity were stu died. The results of these studies show that only the type of surfacta nt has an impact on the nanoparticle dimensions. The release rate of a mpicillin from PECA nanoparticles at pH 7.4 (extracellular value pH) p erformed either with and without esterases, show that the drug release is considerably increased in the presence of these exzymes. The resul ts of drug release study at pH 1.1 (simulated gastric juice) are very interesting. This study has evidenced that the 70% of ampicillin is re leased quickly, while the remaining fraction is firmly incorporated in nanoparticles. The,released ampicillin is quickly degraded in acid me dium while the entrapped fraction is protected from acid degradation a nd afterwards, when nanoparticles reach the small intestine, can be re adily released in the presence of esterases. This result could be expl oited for the oral administration of the ampicillin-PECA system. Final ly, studies of antimicrobial activity of prepared systems evidenced th at ampicillin-loaded PECA nanoparticles exhibit an activity equal or h igher than the free drug. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.