Spray-dried microparticles containing polymeric nanocapsules: Formulation aspects, liquid phase interactions and particles characteristics

Spray-dried microparticles containing polymeric nanocapsules: Formulation aspects, liquid phase interactions and particles characteristics
Received 18 January 2006; revised 9 June 2006; accepted 17 June 2006. Available online 23 June 2006.
Patrice Tewa-Tagnea, b, St?phanie Brian?ona, b, , and Hatem Fessia, b
International Journal of Pharmaceutics
Volume 325, Issues 1-2 , 15 November 2006
ScienceDirect
Copyright ? 2006 Elsevier B.V. All rights reserved.
aLaboratoire de G?nie Pharmacotechnique et Biogal?nique, ISPB Facult? de Pharmacie (UCB Lyon I), 8, avenue Rockefeller, 69373 Lyon Cedex 08, France
bLaboratoire d?Automatique et de G?nie des Proc?d?s (UMR CNRS-UCB Lyon I - 5007), 43, boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex, France
Abstract
Up to now, the full potential of polymer-based nanoparticles is not yet exploited because of a lack of stability when conserved in aqueous medium. The present paper reports the water elimination from nanocapsules (NC) dispersions by means of the spray-drying technique with the aim to achieve dried solid forms of interest using colloidal silicon dioxide as drying auxiliary. The influence of formulation parameters on the suspension behaviour and on the powders characteristics was also evaluated. Our findings demonstrated that the mixing protocol, the concentrations of both NC and silica are crucial parameters that affect the feed behaviour and the spray-dried particles characteristics. Interactions occurring in the feed are directed by hydrogen bounds and were more sensitive to the silica concentration than that of NC as evidenced by rheological measurements. The NC are entrapped within solid dried matrixes following their interaction with silica particles in the feed. SEM analyses of the obtained powders showed spherical separated microparticles formed by the association of NC and silica when they are mixed at adequate concentrations in the feed before spray-drying. On the other hand, fused agglomerated particles presenting NC at their surface, characterised by irregular shapes and a strong adhesiveness were prepared when the silica concentration was not sufficient. The surface composition of the spray-dried powders was investigated using the ESCA technique and revealed the NC exclusion from the surface to obtain powders suitable for further handling.
Keywords: Nanocapsules; Formulation; Feed rheology; Spray-drying; Microparticles
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