Browsing by Subject "X-ray powder diffraction"
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(2013)The pet medication industry is growing but there are still challenges especially in feline medication. Palatable flavours, efficient taste masking technologies and easily administrable dosage forms are needed to facilitate feline medication. Based on the literature review, there is only little information about cat's preference to individual flavours. The methods for palatability testing should be improved to achieve reliable results. Most common taste masking technologies are flavouring and tablet coating. In experimental section different flavours for taste masking were studied. Five main flavours were selected: phenylalanine, leucine and methionine as possibly good flavours and arginine and denatonium benzoate as bad flavours. In preformulation experiments tableting characteristics, thermal behaviour and crystal structure of flavours were analysed. The aim was also to study their possible incompatibilities with tablet excipients. The main compatilibility study method was X-ray powder diffraction (XRPD), but differential scanning calorimetry (DSC) was also used. Excipient povidone (PVP) was incompatible with nearly all of the main flavours. The use of lactose as an excipient was excluded because of the risk of the Maillard reaction. In tableting studies a tablet mass containing microcrystalline cellulose (MCC), calcium hydrogen phosphate dihydrate, mannitol, hydroxypropyl cellulose (HPC), crospovidone, talc and sodium stearyl fumarate was produced. Minitablets of diameter 3 mm without any flavours were compressed. Also minitablets with flavours phenylalanine and denatonium benzoate were compressed. Minitablets complied with the European Pharmacopoeia tests for uniformity of mass, disintegration and friability. However, characterization and handling of minitablets was found to be challenging due to very small size of the tablets. Minitablets are a promising technology for facilitating feline medication in the future.
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(2023)Solids most commonly come in two broad forms: crystalline or amorphous. Crystalline solids have a regular, organized long-range structure of atoms and crystals, and are characterized by having a distinct shape, specific volume, and melting point. They can also have multiple polymorphs. On the other hand, amorphous solids do not usually have a regular long-range atomic and crystal structure and their molecules are more easily separated, which makes them more soluble in their surroundings compared to crystalline solids. However, despite this, short-range order can also occur. To improve the solubility of crystalline solids, co-amorphous systems can be created by mixing together two or more chemically different compounds in a way that they don't form a regular crystalline structure, but rather an irregular, amorphous one. Co-amorphous systems can be analyzed qualitatively or quantitatively. Qualitative analysis is often the main focus when studying amorphous matter, as it can be difficult to accurately quantify these materials using techniques based on crystal structures. Additionally, many amorphous systems are made up of complex mixtures of polymers with different chemical and physical properties. This study aimed to determine the most effective method for obtaining quantitative information about the co-amorphization of indomethacin and tryptophan. Three analytical techniques were used for this purpose: differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), and Raman spectroscopy. The co-amorphous system was created by mixing together α-indomethacin and tryptophan, γ-indomethacin and tryptophan, and amorphous indomethacin and tryptophan. This study showed that DSC, XRPD, and Raman spectroscopy are effective in providing quantitative information about crystallinity and crystal size. These techniques were able to accurately detect and characterize discrete residual crystals, and were able to measure and quantify the amount of these substances. Even though these methods may not be able to detect nanoscale structures with precision, they still provided valuable information about the crystalline and amorphous nature of the samples studied. Additionally, the fact that similar quantitative results were obtained using different analysis methods further supports the reliability of these techniques. Of all the techniques discussed, Raman spectroscopy was able to identify even small residual crystals, resulting in the highest calculated crystallinity percentage.
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