Graft copolymers of ethyl methacrylate on waxy maize starch derivatives as novel excipients for matrix tablets: physicochemical and technological characterisation.
ABSTRACT Nowadays, graft copolymers are being used as an interesting option when developing a direct compression excipient for controlled release matrix tablets. New graft copolymers of ethyl methacrylate (EMA) on waxy maize starch (MS) and hydroxypropylstarch (MHS) were synthesised by free radical polymerization and alternatively dried in a vacuum oven (OD) or freeze-dried (FD). This paper evaluates the performance of these new macromolecules and discusses the effect of the carbohydrate nature and drying process on their physicochemical and technological properties. Grafting of EMA on the carbohydrate backbone was confirmed by IR and NMR spectroscopy, and the grafting yields revealed that graft copolymers present mainly a hydrophobic character. The graft copolymerization also leads to more amorphous materials with larger particle size and lower apparent density and water content than carbohydrates (MS, MHS). All the products show a lack of flow, except MHSEMA derivatives. MSEMA copolymers underwent much plastic flow and less elastic recovery than MHSEMA copolymers. Concerning the effect of drying method, FD derivatives were characterised by higher plastic deformation and less elasticity than OD derivatives. Tablets obtained from graft copolymers showed higher crushing strength and disintegration time than tablets obtained from raw starches. This behaviour suggests that these copolymers could be used as excipients in matrix tablets obtained by direct compression and with a potential use in controlled release.
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ABSTRACT: Abstract In recent years, polysaccharides, including starch and its derivatives, have been widely used in the pharmaceutical industry, including as diluents, fillers, binders, disintegrants and glidants. The use of native starch as excipient in extended-release tablets is limited due to its low compactibility and enzymatic degradability, leading to the formation of weakly structured tablets. To overcome these limitations and expand the application of starch as an excipient, researchers have modified starch by physical and chemical methods, as well as by enzymatic hydrolysis. Some starch derivatives, including retrograded starch, pregelatinized starch, carboxymethyl starch, starch acetate, cross-linked starch and grafted starch have recently been introduced as excipients in oral tablets to control drug release. In this review, applications of starch and its derivatives as extended release excipients are reviewed and future frontiers are described.Drug Delivery 05/2014; · 2.02 Impact Factor
Chapter: Starch: From Food to Medicine02/2012; , ISBN: 978-953-307-916-5
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ABSTRACT: The idea, the concept, and the term, that is cloud computing, has recently passed into common currency and the academic lexicon in an ambiguous manner, as cloud dust is being sprinkled on an excess of emerging products. Exorcising complexity and protecting against the caprice of the moment, this paper explores the notion behind the hype of cloud computing and evaluates its relevance to electronic government and electronic voting information systems. This paper explores increasing participation and sophistication of electronic government services, through implementing a cloud computing architecture. From an Information and Communication Security perspective, a structured analysis is adopted to identify vulnerabilities, involved in the digitalization of government transactions and the electoral process, exploring the notion of trust and transparency within this context. In turn, adopting a cloud computing approach for electronic government and electronic voting solutions is investigated, reviewing the architecture within the previously described context. Taking a step further, this paper proposes a high level electronic governance and electronic voting solution, supported by cloud computing architecture and cryptographic technologies, additionally identifying issues that require further research.Government Information Quarterly 04/2011; 28(2):239–251. · 1.42 Impact Factor