Spray-dried Microspheres Based on Chitosan and Lecithin Cyclosporin A Delivery System

Ž. Davosir Klarić, A. Hafner, M. Dürrigl and J. Filipović-Grčić

Abstract
Conventional and composed cyclosporin A (CsA)-loaded polymeric microspheres (MS) were prepared by spray-drying of CsA/chitosan one-phase system (solutions) and CsA/lecithin/chitosan two-phase system (suspensions). Microspheres were characterised in terms of production yield, entrapment efficiency, size distribution, zeta-potential, thermal properties, swelling ability and drug release profile. Conventional MS were characterised by mean diameter ranging from 1.15 ± 0.91 to 1.27 ± 0.84 μm and CsA entrapment efficiency varying from 72.6 to 87.3%. Composed MS were characterised by larger mean diameter (1.32 ± 1.08 to 1.53 ± 1.15 μm) and higher CsA entrapment efficiency (86.6–94.3%) compared to the corresponding conventional MS. Only composed MS showed swelling ability, which was proportional to chitosan base content in the preparation. In vitro CsA release profile depended on both, the type of the spray-dried system and the chitosan used, as these factors were crucial in determining CsA entrapment pattern and swelling/dissolution ability of MS.

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Keywords
chitosan, lecithin, microspheres, nanoparticles, cyclosporin, spray-drying, ocular delivery