Authors:A. Fehér, E. Csányi, I. Csóka, Anita Kovács and I. Erős
The interactions between surfactant and water were studied thermoanalytically focusing on the lyotropic liquid crystalline and microemulsion region in four ternary systems containing Cremophor EL and Cremophor RH40 as surfactants, neutral oil and isopropyl myristate as oily components. Subzero temperature DSC (SZT-DSC) measurements were carried out to determine the quantity of the bound water forming a hydration layer in surfactant microstructures, and the amount of free water, which has physico-chemical properties not much different from those of pure water. The variation of the surfactant:bound water ratio in the function of water concentration was also investigated. Phase changes detected by the SZT-DSC measurements were confirmed by polarization-microscopic and rheological investigations.
Authors:P. Sipos, A. Szabó, I. Erős and Piroska Szabó-Révész
A study was made of the possibilities of gradually decreasing the concentration of the toxic organic solvent in the process
of microsphere preparation. Ammonio methacrylate copolymer-based microspheres were prepared by spray drying or conventional
solvent evaporation techniques, and compared. The formulations were designed by varying the preparation methods and the concentrations
of four polar cosolvents as independent variables.
DSC was used to study the relationship between the changes in the independent variables and three of the main thermal events
of the microspheres. Raman spectroscopy was used to investigate and confirm the possible interactions between drug and copolymer.
Appropriate choice of the independent variables led to the molecularly dispersed drug in the polymer matrix. It was demonstrated
that only the nature of the preparation method caused significant variations in the structure and thermal behaviour of the
Authors:R. Amin Kreaz, Cs. Novák, I. Erös and M. Kata
Solid formulas obtained between furosemide and two β-cyclodextrin derivatives (HP-β-CD and RAMEB) were prepared by different
methods and in various ratios (1:1 and 1:2). The inclusion complex formation between the drug and the β-CDs of 1:1 ratio was
evaluated by mean of thermal analysis (DSC, TG and EGD). Supplementary techniques, such as X-ray diffraction, were also applied
to interpret the results of the thermal study of physically mixed and kneaded products. Both studies demonstrated the formation
of inclusion complexes in all samples except the physical mix samples; formation of true inclusion complexes was then possible
only when the components were in melted form. The complexation increased the solubility and the rate of dissolution of the
drug. RAMEB was found to be a better complexing agent than HP-β-CD; in both ratios it can be selected as a vehicle in furosemide
Authors:Á. Gombás, P. Szabó-Révész, G. Regdon and I. Erős
Mannitol and sorbitol are widely used in the pharmaceutical and food industry. There are some technological procedures such
as spray-drying, freeze-drying, tablet compression, during which there is a possibility of heat effect. The purpose of this
work was to study the thermal properties of sorbitol, mannitol and their mixtures. Furthermore, these materials and their
tablet pressing were studied after melting and solidification. The results of the study prove that the use of sorbitol or
mannitol alone is disadvantageous in melt technology. The use of mannitol is limited because of its high melting point (165C)
and the polymorph transition after melting. Sorbitol (melting point: 96.8C) vitrifies from melt, therefore it is hard to
handle during further processing. The melting point of the eutectic mixture (1.8% mannitol and 98.2% sorbitol) was 93.6C.
This mixture was unsuited for pressing because of its glassy property. Our results showed that the most favourable composition
was the mixture of 30% mannitol and 70% sorbitol (melting point: 131.8C) for tablet formulation. This mixture can be recommended
for the formulation of such lozenge and hard candy tablets, where the active ingredient decomposes at higher temperature (>131.8C).
Authors:G. Regdon, A. Kósa, I. Erős and K. Pintye-Hódi
Differential scanning calorimetry (DSC) was used in the investigation of the behaviour of coating free films. The films were
produced from two film-forming polymers which are chemically different but equally used for producing controlled-release dosage
forms: Eudragit NE 30 D (synthetically produced polymethacrylate copolymer) and LustreClear product (mixture containing natural
and semi-synthetic components: microcrystalline cellulose, hydroxy-ethyl cellulose, carrageenan and polyethylene glycol).
During their comparative analysis the characteristic parameters of the DSC curves obtained with dynamic measurement method
were used and their changes as a function of storage conditions and storage time were observed. It was found that the thermoanalytical
behaviour of the examined methacrylate-based Eudragit NE and cellulose-based LustreClear films was different. The specific
enthalpy change of Eudragit NE fresh films was very little, but it increased considerably during storage. The specific enthalpy
change of LustreClear films was much greater but its value shows only a slight further increase during storage. The results
obtained help to choose the proper temperature for coating and drying.
Authors:G. Zapantis, G. Zapantis, Ildikó Csóka, E. Csányi, E. Csányi, G. Horváth, G. Horváth, I. Erős and I. Erős
The aim of this study was to evaluate the systemic absorption of the topically administered ketamine using different vehicles and additives, in order to develop a transdermal therapeutic system (TTS) of this drug. After the application of different ketamine preparations (1% in hydrogel, o/w cream, or organogel) the ketamine appeared in the blood. The lowest level could be observed with o/w cream, while the highest concentration was achieved by means of the hydrogel system, however this difference was not significant. Further studies are going to be performed with higher drug concentrations for the characterization of the differences in the pharmacodynamics of the drug with different vehicles and to evaluate the correlation between the in vitro and in vivo absorption.
Authors:Anita Kovács, I. Csóka, Magdolna Kónya, E. Csányi, A. Fehér and I. Erős
The properties of the inner and the external aqueous phases, were studied in w/o/w multiple emulsions with light microscopic image analysis and differential scanning calorimetry (DSC). The importance of multiple emulsions lies in the presence of these aqueous phases, making them available for sustained, controlled drug delivery systems. Differentiation of these two aqueous phases, studying the effect of manufacturing technology on droplet structure, quantitative determination of phase volumes and any changes occurring during storage are essential when planning w/o/w emulsions. The present study uses microscopic observations combined with DSC measurements in order to identify the formed structure, at developmental stage in case of different components, preparation methods, and stirring rates. These tools are beneficial during manufacturing as in process controls, or to ensure product quality.
Authors:M. Kónya, M. Sorrenti, F. Ferrari, S. Rossi, I. Csóka, C. Caramella, G. Bettinetti and I. Erős
Thermogravimetric and rheological investigations of oil/water (o/w) creams prepared with different types of surface-active
agents (non-ionic, non-ionic POE-free, ionic) were carried out. Thermogravimetry was aimed at the indirect study of the water
bond mechanism in o/w creams and the influence of the composition, type and concentration of the mixed emulsifier on the binding
of water incorporated in the structure (interlamellar, bulk) and on the binding proportions. The microstructural changes during
application were studied with respect to the stability of the lamellar bilayer.
Authors:Z. Aigner, H. B. Hassan, O. Berkesi, M. Kata and I. Erős
Summary Inclusion complexation between dimethyl-β-cyclodextrin and a very poorly water-soluble serum lipid-regulating agent, gemfibrozil, was studied. Products were prepared by several methods (physical mixing, kneading, spray-drying and ultrasonic treatment) in four different molecular ratios (2:1, 1:1, 1:2 and 1:3). The possibility of complex formation between the drug and the host molecule was studied by thermal analysis. Supplementary techniques, such as Fourier transformation-infrared spectroscopy and X-ray diffractometry, were also applied to interpret the results of thermal study of the products.
Authors:Mária Szűcs, Patrizia Vaghi, Giuseppina Sandri, M. Bonferoni, Carla Caramella, Piroska Szabó-Révész and I. Erős
Polymeric emulsifiers provide exceptional stability to oil-in-water, water-in-oil or multiple emulsions by their steric stabilization.
Pemulens as polymeric emulsifiers are able to stabilize o/w type emulsions because their short lipophilic part integrates into the oil droplets while their long hydrophilic part forms
a micro gel around the droplet. In our present study the microstructure and integration of the polymeric emulsifier at the
water-oil interface was investigated with thermogravimetric and microscopical methods. It was established that depending on
the amount of both of the polymeric emulsifier and added coemulsifier the microstructure of the system changes.