pH-sensitive microparticles prepared by an oil/water emulsification method using n-butanol.
ABSTRACT Commonly, the microencapsulation of a lipophilic drug in pH-sensitive polymeric matrix via an ordinary oil/oil emulsification allows for entrapping limited drug amounts due to its loss into the external phase. Here, we propose a microencapsulation method on the basis of an oil/water emulsification method using n-butanol. Eudragit S100 microspheres were prepared by an oil/water emulsification solvent extraction method trapping ibuprofen as lipophilic model drug. Morphological analyses of the obtained particles showed a spherical shape and a sponge-like internal structure. In order to increase the entrapment efficacy several preparation parameters were optimized, such as theoretical drug load and surfactant concentration in the external phase. The particle size varied slightly around 170 microm, barely influenced by the modified process parameters. Drug leakage at pHs below the polymer dissolution pH was highest with microspheres prepared at low theoretical drug loading and low surfactant concentrations. In vitro drug release was found to be strongly pH-dependent; ibuprofen was retained in microspheres at pH 2.0 (<20% release within 4 h) whereas a higher leakage was observed at pH 5.5 and a nearly immediate drug release was obtained at pH 7.4. The use of n-butanol was found to be a new promising alternative for the preparation of pH-sensitive microspheres by an oil/water emulsification.
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ABSTRACT: The main purpose of the present investigation was to develop a novel enteric mucoadhesive formulation of (-)-epigallocatechin-3-gallate (EGCG), a green tea catechin, with the aim of avoiding its severe degradation in the gastrointestinal tract and therefore improving pharmacological effects. The EGCG-loaded microspheres (EGCG/MS), containing Eudragit(®) S100, were prepared with an emulsion solvent diffusion method in aqueous PVA solution. The EGCG/MS with a diameter of 16 μm exhibited pH-dependent controlled release of EGCG with limited initial burst release, and the Eudragit(®) S100-based MS also had moderate bioadhesive property in isolated small intestine of rats. There appeared to be marked degradation of EGCG in acidic solution (pH 1.2) and neutral buffer (pH 6.8) containing intestinal microsomal fraction, although significant improvement in chemical and metabolic stability of EGCG was observed in the EGCG/MS, possibly due to the controlled release and/or bioadhesion. From these findings, newly prepared EGCG/MS might be of clinical importance in both stabilizing and delivering EGCG for treatment of intestinal diseases.International Journal of Pharmaceutics 03/2011; 410(1-2):111-3. · 3.99 Impact Factor
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ABSTRACT: In this study we produced microcapsules using layer-by-layer adsorption of food-grade polyelectrolytes. The shell was built with alternating layers of ovalbumin fibrils and high methoxyl pectin. By varying the number of layers, the release of active ingredients can be controlled – increasing the number of layers of the shell from 4 to 8, decreases the release rate by a factor 3. The formation of the capsules involves merely standard operations that can easily be scaled up to industrial production.Food Hydrocolloids - FOOD HYDROCOLLOID. 01/2011; 25(3):307-314.