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EFFECT OF TEMPERATURE ON THE ENCAPSULATION OF AMOXICILLIN
MICROPARTICLES BY SAS PROCESS
A. Montes (*); M. D. Gordillo; C. Pereyra and E. J. Martínez de la Ossa Department of Chemical Engineering and Food Technology, Faculty of Sciences, University of Cádiz Phone: +34-956-016-458. Fax: +34-956-016-411 Drug encapsulation processes has been an active field of research and innovation during past decades1-3 due to the benefits as taste and smell masking, protection from rapid drug degradation, targeting delivery, control of the release rate, and prolonged duration of bioactive agents. The use of supercritical CO2 allows avoiding the conventional encapsulation process drawbacks since eliminates or reduces the use of organic solvents; the separation of the supercritical CO2 from the product can be easily carried out; it is possible to obtain solvent-free products; provides an inert medium suitable for processing easily oxidable and thermo labile substances and minor environment impact. Thus SAS process has been used to encapsulate amoxicillin (AMC), one of the most widely prescribed antibiotics, with ethylcelullose (EC), a hydrophobic polymer used in a variety of applications such as sustained release and taste masking. AMC microparticles previously obtained by SAS process4 were suspended into a solution of EC in dichloromethane, and then sprayed into the vessel trough a nozzle of 100 µm. A rapid mutual diffusion between the supercritical CO2 and the organic solvent causes supersaturation of the polymer solution, leading to nucleation and precipitation of the polymer to encapsulate the AMC microparticles, nuclei for the precipitation of the polymer. Temperatures of 35, 50 and 65ºC at 150 bar of pressure into the vessel have been assayed in order to find out the influence of this parameter on the encapsulation process. All the experiments led to spherical or quasi spherical microparticles of AMC and EC. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and High- Performance Liquid Chromatography (HPLC) analyses were carried out. Moreover, AMC encapsulated-microspheres were evaluated for encapsulation efficiency and loading and their ability to release AMC into SIF and SGF. It can be observed that higher operating temperatures led to higher particle size of encapsulates. Fig.1. SEM images of microparticles of amoxicillin and ethylcellulose obtained by SAS Acknowledgments
We gratefully acknowledge the Spanish Ministry of Science and Technology (Project CTQ2007-67622 and CTQ2010-19368) for financial support. References
[1] R. Falk, T.W. Randolph, J.D. Meyer, R.M. Kelly, M.C. Manning, Controlled release of ionic compounds from poly (L-lactide) microspheres produced by precipitation with a compressed antisolvent, J. Controlled Release 44 (1997) 77-85. [2] B. F. Gibbs, S. Kermasha, I. Alli, C.N. Mulligan, Encapsulation in the food industry: a review, International J. Food Science Nutrition 50(3) (1999) 213-224. [3] C. Duclairoir, A. M. Orecchioni, P. Depraetere, E. Nakache, α-Tocopherol encapsulation and in vitro release from wheat gliadin nanoparticles, J. [4] A. Montes, A. Tenorio, M.D. Gordillo, C. Pereyra, E.J. Martínez de la Ossa Screening design of experiment applied to supercritical antisolvent precipitation of amoxicillin: Exploring new miscible conditions. J. Supercritical. Fluids 51 (2010) 399-403.

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