Effect of eudragit type polymers on the drug release from magnesium oxide granules produced by laboratory fluidization

I. Rácz, R. Zelkó, E. Bihari, M. Bucsek

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7 Citations (Scopus)


The differences in the bioavailability of different drug products are most frequently caused by differences in the dissolution rates of the active ingredient. In case of magnesium oxide the drug release can be directly determined by reaction kinetics method based on acid neutralization. For a more precise study of the factors influencing the kinetical characteristics of the neutralization rates it is advisable to use homogeneous granule fractions. Before the granulation the substance was pretreated with silicone oil. The granulation of the obtained grains having hydrophobe surface was carried out in an AEROMATIC STREA-I type laboratory fluidization equipment with Eudragit polymer solved in isopropyl alcohol. For determining the acid neutralization kinetics of the granules the "constant pH" method and the Rossett-Rice test were used. As a result of the granulation the neutralization rate decreased. The granules can be considered as an Eudragit matrix which contains the pretreated magnesium oxide in embedded form. During the chemical reaction the resulted salt (magnesium chloride) leaves the surface of the unreacted magnesium oxide unless having a chemical reaction with the polymer. Meanwhile the residual matrix forms a mesh which increases the viscosity of the solution and the thickness of the diffusion layer. The dissolution rate decreases in both cases. Under the same conditions the kinetic values of the neutralization change by several magnitudes depending on the utilized methods. In this way different systems of medicine, which alter their reaction capacity according to the expected physiological purposes, can be created.

Original languageEnglish
Pages (from-to)2085-2096
Number of pages12
JournalDrug development and industrial pharmacy
Issue number18
Publication statusPublished - Jan 1 1995


ASJC Scopus subject areas

  • Pharmacology
  • Pharmaceutical Science
  • Drug Discovery
  • Organic Chemistry

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