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. Near-infrared spectroscopy was used to analyse the diffuse-reflectance characteristics of the prepared multi-particulate matrices without destructive sample preparation. A 2-factor, 3-level face-centred central composite design was selected to construct a second-order polynomial model which described the effect of particle size and amount of coating on the intensity of the diffusely reflected light. A non-linear model was used to demonstrate the effect of the selected parameters on the intensity of the reflected light; good correlation was obtained between experimental and predicted results. The results indicated that the extent of coating and the particle size of the examined systems in the selected particle size-range modified the intensity of the reflected light. It can be concluded that near-infrared spectroscopy is a sensitive means of measuring not only the particle size of powders (substrates and their mixtures), but also that of coated multi-particulate systems.

[Solution kinetics of magnesium oxide containing granules produced by laboratory scale fluidization]. / Laboratóriumi fluidizációs eljárással elöállított magnézium-oxid tartalmú granulátumok szétesés- és oldódáskinetikai vizsgálata.

In practice of manufacturing industrial pharmaceutical products, the technique of fluidization has been used extensively in the past decades. The authors studied the magnesium oxide-containing granulates made by fluidization granulation in laboratory, to optimize the process, to determine the neutralization kinetic parameters of granulates, to establish the connections between the method of granulation and the release of active substances. According to our findings, the pharmaceutical product's characteristics in the aspects of physics, chemistry, stability and bioavailability may remarkably change without fixing the border conditions of parameters within limits.

[Effect of physicochemical properties of polyethylene glycol derivatives on drug release from wax matrices]. / Poli(etilénglikol)-származékok fizikai-kémiai tulajdonságainak hatása viasz-mátrixok hatóanyag-leadására.

The purpose of the present study was to investigate the effect of the various types and amounts of polyethylene glycols on the potassium chloride release from wax matrices. Potassium chloride as a highly water-soluble model drug was embedded into wax containing surfactants to produce sustained release dosage form. Various kinds of polyethylene glycols were chosen to control the dissolution profile. The dissolution profile of the matrix samples was characterized by the Weibull distribution. The physico-chemical characteristics--surface tension, HLB value, refractive index--of the aqueous solutions of the polyethylene glycols were also determined. On the basis of the examined physicochemical characteristics of various polyethylene glycols it is possible to select the optimal concentration of surfactant to formulate matrix dosage forms of required dissolution profile.

[Evaluation of substrate-binder interfacial interactions]. / Szubsztrát-kötóanyag hatáfelületi interakciók jellemzése.

Substrate-binder interfacial interactions were evaluated on the basis of the physico-chemical and mechanical properties of granules and compressed samples. Linear relationship was found between the breaking strength, the diffuse reflectance and the binder content of the examined granule-systems and compressed samples. The increasing amount of binder in the granules improved the adhesive interaction existing between the substrate and the binder. Our results indicate that the mechanical properties of the single particles as well as of the compressed samples were basically determined by the physico-chemical interactions of the substrate-binder interfacial layer. The qualitative and quantitative evaluation of these interactions has a decisive impact on the formulation and in process control of solid dosage forms of optimal mechanical properties.

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.