Mihály Kata

Quantitative Determination of Crystallinity of α-Lactose Monohydrate by DSC

In pharmaceutical practice it is important and useful to know the crystallinity of materials and to monitor it during formulation development, production processes and storage. The purpose of this study was to assess the quantitative capability of DSC for determining crystallinity in crystalline/amorphous powder mixtures and to compare the accuracy of the DSC method with that of conventional powder X-ray diffraction. Alpha-lactose monohydrate was chosen as the model material. On the basis of this study it can be concluded, that DSC method can be applied safely for semiquantitative evaluation of the crystallinity of lactose samples consisting of an amorphous content higher than 20%.

Thermoanalytical studies on complexes of ketoconazole with cyclodextrin derivatives

Inclusion complexation between cyclodextrin derivatives (hydroxypropyl-β-cyclodextrin and methyl-β-cyclodextrin) and a very poorly water-soluble antifungal agent, ketoconazole, was studied. Solid products were prepared by physical mixing, kneading and spray-drying methods in four molecular ratios: 2:1, 1:1, 1:2 and 1:3. The possibility of complex formation between the drug and the cyclodextrins was studied by thermal analysis. Supplementary techniques, such as X-ray diffractometry and Fourier transformation-infrared spectroscopy, were also applied to interpret the results of the thermal study of the products.

Investigation of tenoxicam and γ-cyclodextrin binary and ternary complexes

Tenoxicam is a widely used non-steroidal anti-inflammatory drug (NSAID). Itscomplexation with cyclodextrin was studied in order to improve its aqueoussolubility and to decrease its side-effects. Two- and three-component systems inseveral mole-ratios were prepared by means of two different methods. The drugliberation profile, the in vitro membrane diffusion and the n-octanol/water partitioncoefficient were investigated. The presence of complexes was detected via thermoanalyticaland X-ray diffractometric studies. On the basis of these data, several compositionswere selected for incorporation into topical dosage forms.

Preparation and Investigation of Inclusion Complexes Containing Nifluminic Acid and Cyclodextrins

Nifluminic acid (N) is a frequently used anti-inflammatory drug,but its poor aqueous solubility is a disadvantageous property. Inclusion complexation with cyclodextrinderivatives (CDs) affords a possibility to increase its solubility properties. For thispurpose, different CDs were used, primarily hydroxypropyl-β-CD (HP-β-CD), to prepareproducts by powder mixing or kneading in four molecular ratios. The dissolution and in vitromembrane diffusion of the products were investigated. The wetting angles of pure N andHP-β-CD and of the products, and the n-octanol/water partition coefficients were determined.The interaction, leading to complex formation between the components of the products was examined by thermoanalytical methods.

Investigation of Ethacrynic Acid and Random-methyl-β-cyclodextrin Binary Complexes

Cyclodextrin complexation was applied to achieve better aqueous solubility of the drug and to formulate suppositories. Binary products were prepared in several mole ratios by two different methods. The dissolution profiles and in vitro membrane diffusion behaviour of the compositions were investigated. Thermoanalytical studies were performed in order to confirm inclusion complex formation. Compositions were selected for further detailed investigations and for incorporation into suppository dosage form.