Browsing by Subject "co-crystal"
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(2012)In medicines APIs are most oftenly at solid form. Crystal forms are more stable than amorphic solid form. Crystals are hold together by intermolecular interactions. Strongest and most common intermolecular interaction in crystals is hydrogen bond. Crystallisation is affected by thermodynamics and kinetics. Same phenomena effect also dissolving of crystals. New APIs often have a poor water solubility which makes them difficult to use. Cocrystals are one way to improve physical characteristics of molecules and most of all solubility. In co-crystals two different solid molecules are crystalliced in a same crystall lattice. Itraconatzole is an API with a poor water solubility. Itraconatzole can form cocrystals with many bicarbocsylicacids. The smallest bicarbocsylicacid that had formed co-crystal with itraconazole is malonic acid. The purpose of the experiment was to grow itraconazole malonic acid co-crystal, which is big enough for single crystall x-ray diffraktion. With SXRD it is possible to find out how molecyles are placed in a crystall lattice. For SXRD the single crystal is not allowed to have a single mistake in its lattice. Itraconazole and malonic acid were dissolved to 1,2-dichloroethane-2-butanone and tetrahydrofurane-chloroform for growing up a single crystal. Crystallisation methods used were evaporation of solvent, adding antisolvent and cooling down of solution. Formed crystalls were analysed with DSC, raman, XRD and TGA. It was succeeded to crystallise itraconazole malonic acid co-crystals with used methods. The formed crystalls were needlelike and packed in small drifts. Any crystall big enough for SXRD was not succeeded to grow up with the methods used. Growing up a bigger co-crystal needs the use of new methods or optimation of the ones used in this experiment.
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(2023)Poorly water soluble active pharmaceutical ingredients cause problems for the drug development. Solid state modification offers one approach to overcome the issue. In this study, co-amorphous systems and co-crystals were prepared with indomethacin at molar ratio of 1:1 using nicotinamide as a co-former. Co-amorphous systems were prepared by two different preparation methods: melting the physical mixture and then quench cooling it with liquid nitrogen and dry milling with a ball mill. Co-crystals were prepared by liquid-assisted ball milling. After that, the properties, dissolution, and physical stability of the formed formulations were investigated and compared. The characterisation methods were differential scanning calorimetry, X-ray powder diffraction, Fourier-transform infrared spectroscopy, polarised light microscope and scanning electron microscope. In addition, the solubility and physical stability of the formulations were investigated. Co-amorphous systems were successfully prepared by quench cooling the melt and co-crystals by liquid-assisted ball milling. Dry milling did not induce the formation of co-amorphous systems. In the intrinsic dissolution test, both the co-amorphous system and co-crystal enhanced the dissolution of crystalline indomethacin. When examining the dissolution rate with the paddle apparatus, it was observed that the co-crystal had the highest dissolution rate among both powder and tablet samples. The co-amorphous powder sample floated on the surface of dissolution medium which impeded the dissolution of indomethacin. However, co-amorphous tablet sample showed a higher dissolution rate than crystalline indomethacin. Stability testing (25 °C, 18 %RH) showed that the co-amorphous system recrystallised into a co-crystal after two weeks of storage, while the co-crystal was found to stay stable the whole study period.
Now showing items 1-2 of 2