E. Bihari

Effect of chemical properties on drug release from hydrophobic matrices

The drug release of modified release matrix systems is often governed by erosion as well as by diffusion through the matrix. The purpose of the present work was to study the release kinetic parameters of inorganic and organic water soluble drugs from hydrophobic wax matrix systems, produced by melt coating. The drug release process was investigated both experimentally and by means of mathematical models. Different models (first order, cube root, square root, two-third root) and the Weibull distribution were applied for the evaluation of the drug release data. On the basis of our results, it can be concluded that not only the ratio but the chemical characteristic of the drug and the matrix base material as well determine the rate of drug release.

Effect of Polysorbates on Drug Release from Wax Matrices

The purpose of this study was to investigate the effect of various types and amounts of polysorbates on potassium chloride release. Potassium chloride, which is a highly water-soluble model drug, was embedded into wax (containing surfactants) to produce a sustained-release dosage form. Various kinds of polysorbates were chosen as surfactants to control the dissolution profile. The release of the model drug was tested by rotating paddle method of USP 23 and the dissolution process was characterized by the Weibull distribution. The surface tension of the aqueous solutions of polysorbates was determined by a computer-controlled Sigma 70 tensiometer. The application of polysorbates in more than 2% concentration did not alter either the release rate of the embedded potassium chloride, or the surface tension values of the aqueous solutions. The results of this study allow the determination of the optimal concentration of polysorbates in the case of the potassium chloride release.

Effect of particle size and coating level on the diffuse reflectance of wax matrices

The aim of this study was to examine the influence of particle size and extent of coating on the diffuse‐reflectance spectra of wax matrices containing embedded potassium chloride.

Mathematical Modeling of Magnesium Oxide Release from Granules Produced by Laboratory Fluidization

AbstractThe particle size usually has an important effect on the rate of drug liberation from sustained release systems. The nature of that effect depends on the geometry of the system and the mechanism of the drug release (1). The aim of the present study was to characterize the relationship between the drug release projile of granules produced by luboratory fluidization and their particle size. The magnesium oxide release from granules-which are of two different particle sizes and contain Eudragit polymer-was investigated both experimentally and with mathematical models. First-order, cube root, square root, and two-thirds root models were applied for the evaluation of the drug release data. Changes in the particle size of the investigated granules altered the drug release profile

Effect of Eudragit Type Polymers on the Drug Release from Magnesium Oxide Granules Produced by Laboratory Fluidization

AbstractThe 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 em...