Article

Graft copolymers of ethyl methacrylate on waxy maize starch derivatives as novel excipients for matrix tablets: physicochemical and technological characterisation.

Departamento Farmacia y Tecnología Farmacéutica, Universidad de Sevilla, Sevilla, Spain.
European journal of pharmaceutics and biopharmaceutics: official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V (Impact Factor: 3.15). 05/2009; 72(1):138-47. DOI: 10.1016/j.ejpb.2008.12.008
Source: PubMed

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.

0 Bookmarks
 · 
159 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The utilization of poly (2-hydroxyethylmethacrylate) grafted agar (Ag-g-P(HEMA)) as a matrix for the controlled release of 5-aminosalicylic acid was investigated. Grafted copolymers of 2-hydroxyethylmethacrylate (HEMA) monomers on agar were synthesized by microwave assisted method. In vitro drug release studies were performed at pH values of 2 and 7 in order to investigate the possibility of pH triggered release for colon targeted drug delivery. Further, the percent grafting vs. t50(the time taken for release of 50% of the enclosed drug) value was studied and the results indicate that it may be possible to develop a programmable drug release matrix based on grafted polysaccharide. Ag-g-P(HEMA) appears to be a useful matrix for controlled release.
    10/2014; 8(4). DOI:10.1007/s11705-014-1452-8
  • [Show abstract] [Hide abstract]
    ABSTRACT: A Highly efficient method was developed for preparing starch-based wood adhesives with high performance, using H2O2, a silane coupling agent and an olefin monomer as an oxidant, cross-linking agent and comonomer, respectively. The effects of various parameters on the shear adhesive strength were investigated in the dry state (DS) and wet state (WS). The results indicated that the bonding strength of starch-based wood adhesives could reach 7.88MPa in dry state and 4.09MPa in wet state. The oxidation could reduce the content of the hydroxyl transforming into carboxyl and aldehyde groups, and the graft copolymerization enhanced the thermal stability, which improved the bonding strength and water resistance. The starch-based adhesive and the fractures in the bonded joints were analyzed via Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The improved properties were attributed to the modified of microstructure of the graft-copolymerized starch-based adhesive. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Carbohydrate Polymers 01/2015; 115:32–37. DOI:10.1016/j.carbpol.2014.08.063 · 3.92 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The present work deals with the development of controlled release tablets of salbutamol sulphate (SS) using graft copolymers of methymethacrylate (St-g-PMMA and Ast-g-PMMA) on starch and acetylated starch. Formulations were evaluated for physical characteristics like hardness, friability, drug release, drug content and weight variations, which fulfilled all the official requirements of tablet dosage form. The release rates from formulated matrix tablets were studied at SGF (pH1.2) followed by SIF (pH6.8). Drug release from the graft copolymer based tablets was found to be sustained upto the 14 h with >75% drug release. The in-vitro release study showed that the graft copolymer based matrix formulations (F3 & F4) exhibited highest correlation value (r2) for higuchi kinetic model and Korsmeyer's model with n values between 0.61 to 0.67 proved that release mechanisms were governed by both diffusion and erosion mechanisum. There was no significant difference in the pharmacokinetic parameters (tmax, Cmax, AUC, Ke, and t1/2) of the graft copolymers matrices and HPMC K100M matrix tablets, indicating their comparable sustained release effect. The potential of graft copolymers to sustain the drug release is well supported by in-vivo pharmacokinetic studies and their adequate physicochemical properties make them promising excipients for controlled drug delivery system.
    Asian Journal of Pharmaceutical Sciences 12/2014; DOI:10.1016/j.ajps.2014.12.003