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.
"c o m / l o c a t e / f o o d h y d possibility to control the interactions between the charged materials . The foundation of multilayers with pH-sensitive characteristics has got considerable attention (Déjugnat & Sukhorukov, 2004; Kietzmann et al., 2009; Mauser et al., 2006; Sukhorukov et al., 2001; Tong et al., 2005). Food proteins have excellent emulsification and film-forming abilities. "
[Show abstract][Hide abstract] 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.
[Show abstract][Hide abstract] ABSTRACT: Microencapsulation of a hydrophilic active (gentamicin sulphate (GS)) and a hydrophobic non-steroidal anti-inflammatory drug (ibuprofen) in alginate gel microparticles was accomplished by molecular diffusion of the drug species into microparticles produced by impinging aerosols of alginate solution and CaCl(2) cross-linking solution. A mean particle size in the range of 30-50 µm was measured using laser light scattering and high drug loadings of around 35 and 29% weight/dry microparticle weight were obtained for GS and ibuprofen respectively. GS release was similar in simulated intestinal fluid (phosphate buffer saline (PBS), pH 7.4, 37°C) and simulated gastric fluid (SGF) (HCl, pH 1.2, 37°C) but was accelerated in PBS following incubation of microparticles in HCl. Ibuprofen release was restricted in SGF but occurred freely on transfer of microparticles into PBS with almost 100% efficiency. GS released in PBS over 7 h, following incubation of microparticles in HCl for 2 h was found to retain at least 80% activity against Staphylococcus epidermidis while Ibuprofen retained around 50% activity against Candida albicans. The impinging aerosols technique shows potential for producing alginate gel microparticles of utility for protection and controlled delivery of a range of therapeutic molecules.
Journal of Drug Targeting 10/2010; 18(10):831-41. DOI:10.3109/1061186X.2010.525651 · 2.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Microparticles produced from synthetic polymers have been widely used in the pharmaceutical field for encapsulation of drugs. These microparticles show several advantages such as drug protection, mucoadhesion, gastro-resistance, improved bioavailability and increased patient's compliance. In addition, it is possible to use lower amount of drug to achieve therapeutic efficiency with reduced local/systemic adverse side effects and low toxicity. Synthetic polymers used for the production of microparticles are classified as biodegradable or non-biodegradable, being the former more popular since these do not need to be removed after drug release. Production of polymeric microparticles can be used for encapsulation of hydrophilic and hydrophobic drugs, by emulsification following solvent extraction/evaporation, coacervation, methods that are revised in this paper, including advantages, disadvantages and viability of each methodology. Selection of methodology and synthetic polymer depends of the therapeutic purpose, as well as simplicity, reproducibility and possibility to scale up.
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