Biomedical subjects

Piroska Szabó-Révész

Publications and source records attributed to Piroska Szabó-Révész.

5 recordsLinked to original sources

PubMed2006

Study of thermal behaviour of sugar esters.

Sugar esters (SEs) are widely used in the pharmaceutical and food industries. They have a wide range of HLB values (1-16), and hence they can be applied as surfactants, or as solubility or penetration enhancers. SEs can be employed in hot-melt technology, because their melting points are low and they decompose only above 220 degrees C. The aims of this work were to study the thermal properties of SEs and to demonstrate differences between SEs with various HLB values. The results revealed that SEs with high or medium HLB values were vitrified by melting. Their glass transitions (T(g)) were determined by modulated differential scanning calorimetry. To visualize the changes in the samples during heating, hot-stage microscopy was used. Hydrophilic SEs were only softened, while lipophilic SEs were melted by heating. After melting and solidification, SEs have partially amorphous layered structures which slowly crystallize in time. Time-dependent solid-state changes (crystalline and amorphous phases) were observed, and analysed by means of differential scanning calorimetry and X-ray powder diffraction.

Calorimetry, Differential Scanning↗

PubMed2006

Development of spherical iron(II) sulfate heptahydrate-containing solid particles with sustained drug release.

The aim of this work was to develop a simple, economic procedure for the manufacturing of coated iron(II) sulfate particles by using a crystallization technique for the development of round particles, followed by coating with a lipophilic material. Several batches of iron(II) sulfate heptahydrate were produced by a cooling crystallization, with variation of the crystallization parameters. The spherical crystals were coated with stearin. The products were characterized for particle size, roundness, bulk density and in vitro drug dissolution. Crystallization was performed from deionized water with no addition of seed crystals and by cooling by applying a linear cooling rate. The developed iron(II) sulfate crystals were round with average diameter of 729+/-165 microm. The best form for the sustained release of iron(II) sulfate was the sample HTP-2 which contained 11% of stearin relative to the iron(II) sulfate. The spherical crystallization of iron(II) sulfate is simple and fast, and does not require a dangerous, expensive solvent. The round particles can coat directly with lipophilic material which results in slow release of iron(II) sulfate and protects the iron(II) from oxidation and inhibits the loss of crystal water. The coated crystals can be filled into capsules to yield the final dosage form.

Chemistry, Pharmaceutical↗

PubMed2006

Physicochemical characterization of meloxicam-mannitol binary systems.

The dissolution behaviour of drugs remains one of the most challenging aspects in formulation development. The anti-inflammatory drug, meloxicam (ME) has poor water solubility. The object of this experiment was to improve the rate of dissolution of meloxicam in capsule form. In order to achieve this, mannitol was used as a carrier in different ratios, in physical mixtures and melted forms. Mannitol, a sugar alcohol, is a cheap and readily available excipient. Differential scanning calorimetry (DSC) and X-ray diffractometry were used to investigate the characteristics of meloxicam-mannitol binary systems. Multivariate curve resolution (MCR) as a chemometric method was applied to interpret the X-ray diffractograms. This is believed to be the first published use of this reasoning for this interpretation. According to the results, the amount of mannitol and the particle size of ME were important factors in the rate of dissolution. To the perfect dissolution of ME, the melt technology was used which resulted in mixed crystals. This technology was made by 10 parts of mannitol and 1 part of ME2 with about 6 microm in average particle size. The interaction (adhesion) between mannitol and ME for physical mixtures was not enough to the perfect dissolution.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2005

Microwave processing of natural biopolymers--studies on the properties of different starches.

In this study, the influence of microwave irradiation on some physico-chemical properties and several pharmaceutical technological parameters of potato and maize starches was investigated. Changes in their habits were observed and decrease in moisture contents caused by the electromagnetic irradiation was determined. The crystalline structures and the micromorphological parameters of the starches were affected by microwave irradiation in different ways depending on the botanical origin of the samples. The tensile strengths of the compacts containing starches were decreased, their wetting properties were enhanced by the thermal process applied. Furthermore, microwave irradiation reduced the surface free energy and the polarity of the compacts significantly. Samples treated by conventional heating were used to compare the effects of microwave irradiation on the examined properties and parameters of these starches.

Biopolymers↗

PubMed2003

Quantitative determination of crystallinity of alpha-lactose monohydrate by Near Infrared Spectroscopy (NIRS).

The purpose of this study was to determine quantitatively the crystallinity in crystalline/amorphous powder mixtures of lactose, to asses the capability of Near Infrared Spectroscopy (NIRS) for quantitative determination of crystallinity and to compare the accuracy of the NIRS method with that of conventional X-ray powder diffraction (XRPD). Amorphous lactose was prepared by spray drying. Samples with different crystallinity were prepared by physical mixing of 100% amorphous and 100% crystalline materials. The samples were characterized by XRPD and NIRS. Analysis was performed on the data sets by multiple linear regression (MLR). There is a close correlation between the predicted and the actual crystallinity of physical mixtures of crystalline and amorphous lactose, determined by NIRS (R(2)=0.9994). NIRS results were compared to the XRPD using the same sample sets. The correlation coefficients was 0.9981. The results showed that NIRS is an useful method for accurately determining low quantities of the crystalline lactose in a physical mixture. Therefore, NIRS can be used for the quantitative determination of crystallinity of materials during pharmaceutical procedures.

Crystallization↗