Differential Scanning Calorimetry
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Pro identifikaci možných interakcí složek v lékových formách se studie obvykle provádějí ve stadiu farmaceutického vývoje. Takové studie mohou předpovídat kompatibilitu aktivních farmaceutických látek a pomocných látek za účelem optimalizace složení přípravku a vhodného nastavení parametrů technologického postupu. Vzájemná kompatibilita některých složek nově vyvinutého neuroprotektivního léčivého přípravku „Neuronukleos“, konkrétně kyseliny thioktové, pyridoxin-hydrochloridu, magnesium-stearátu a mag-nesium-laktátu, byla studována pomocí diferenciální skenovací kalorimetrie (DSC) a infračervené spektroskopie s Fourierovou transformací (FTIR). Žádné interakce mezi kyselinou thioktovou a pyridoxinhyd-rochloridem nebyly pozorovány. Byl vytvořen inter-molekulární komplex kyseliny thioktové a magnesium-stearátu, ve které kyselina thioktová nahrazuje krystalickou vodu magnesium-stearátu. Pro magnesium-laktát nebyly nalezeny žádné významné interakce ani s kyselinou thioktovou ani magnesium-stearátem. V rámci této studie byla prokázána farmaceutická kompatibilita většiny testovaných složek přípravku „Neuronukleos“ s jedinou výjimkou (kyselina thioktová a magnesium-stearát). Předkládaná studie navíc poskytuje hodnotné informace o tepelných jevech v určitém teplotním rozmezí, což je důležité pro nastavení parametrů technologického procesu.
To identify possible interactions of components in dosage forms, studies are usually carried out at the stage of pharmaceutical development. Such studies can predict compatibility of active pharmaceutical ingredients and excipients in order to optimize drug formulation and certain parameters of technological process. Compatibility of some components of a newly developed neuroprotective medicinal product "Neuronucleos", namely, thioctic acid, pyridoxine hydrochloride, magnesium stearate and magnesium lactate, was studied by means of differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). No interactions were observed between thioctic acid and pyridoxine hydrochloride. Formation of an intermolecular complex between thioctic acid and magnesium stearate was established, in which this acid substitutes the crystalline water of magnesium stearate. No significant interactions were found for magnesium lactate with thioctic acid or magnesium stearate. Thus, pharmaceutical compatibility of the most of the tested "Neuronucleos" components was studied and established, with the only exception (thioctic acid with magnesium stearate). Moreover, the present study provides valuable information about thermal effects in a certain temperature range, which is important for setting the technological process parameters.
- Klíčová slova
- farmaceutická kompatibilita, kyselina thioktová, hydrochlorid pyridoxinu, stearát hořečnatý,
- MeSH
- diferenciální skenovací kalorimetrie metody MeSH
- lidé MeSH
- stearany * MeSH
- Check Tag
- lidé MeSH
Citrate buffers are commonly utilized in the field of biomolecule stabilization. We investigate their applicability in the frozen state within a range of initial pHs (2.5 to 8.0) and concentrations (0.02 to 0.60 M). Citrate buffer solutions subjected to various cooling and heating temperatures are examined in terms of the freezing-induced acidity changes, revealing that citrate buffers acidify upon cooling. The acidity is assessed with sulfonephthalein molecular probes frozen in the samples. Optical cryomicroscopy combined with differential scanning calorimetry was employed to investigate the causes of the observed acidity changes. The buffers partly crystallize and partly vitrify in the ice matrix; these processes influence the resulting pH and allow designing the optimal storage temperatures in the frozen state. The freezing-induced acidification apparently depends on the buffer concentration; at each pH, we suggest pertinent concentration, at which freezing causes minimal acidification.
The purpose of this work is to explore the preparation of nanofibrous orally dispersible films (ODFs) by needleless electrospinning from the active pharmaceutical ingredient (API) Tadalafil using particles suspended in a solution of polymers and other excipients. The prepared films were characterized by a combination of scanning electron microscopy, mechanical tests, measurements of the disintegration time and dissolution characteristic, X-ray diffraction, and differential scanning calorimetry. Furthermore, we investigated the impact of lamination pressures in the range of 0 to 5 bars combined with films at various relative humidity values on the mechanical properties of the ODF. An increase in lamination pressure resulted in higher Young's modulus values, with the maximum value observed for a sample laminated at a pressure of 5 bar and the maximum stress and strain of the prepared ODF at a lamination pressure of 1.2 bar. Moreover, there was a significant increase in the disintegration time with increase in lamination pressure. The disintegration time ranged from 0.35 s for non-laminated samples to 12 s for samples laminated at a pressure of 5 bar. On the contrary, the lamination pressure did not reveal to have any impact on the dissolution kinetics. These results confirmed that the lamination pressure can improve the processability of ODFs without affecting the API dissolution kinetics.
The development of an amorphous solid dispersion (ASD) is a promising strategy for improving the low bioavailability of many poorly water-soluble active pharmaceutical ingredients (APIs). The construction of a temperature-composition (T-C) phase diagram for an API-polymer combination is imperative as it can provide critical information that is essential for formulating stable ASDs. However, the currently followed differential scanning calorimetry (DSC)-based strategies for API solubility determination in a polymer at elevated temperatures are inefficient and, on occasions, unreliable, which may lead to an inaccurate prediction at lower temperatures of interest (i.e., T = 25 °C). Recently, we proposed a novel DSC-based protocol called the "step-wise dissolution" (S-WD) method, which is both cost- and time-effective. The objective of this study was to test the applicability of the S-WD method regarding expeditious verification of the purely-predicted API-polymer compatibility via the perturbed chain-statistical associating fluid theory (PC-SAFT) equation of state (EOS). Fifteen API-polymer T-C phase diagrams were reliably constructed, with three distinct API-polymer case types being identified regarding the approach used for the S-WD method. Overall, the PC-SAFT EOS provided satisfactory qualitative descriptions of the API-polymer compatibility, but not necessarily accurate quantitative predictions of the API solubility in the polymer at T = 25 °C. The S-WD method was subsequently modified and an optimal protocol was proposed, which can significantly reduce the required experimental effort.
Some insects rely on the strategy of freeze tolerance for winter survival. During freezing, extracellular body water transitions from the liquid to the solid phase and cells undergo freeze-induced dehydration. Here, we present results of a thermal analysis (from differential scanning calorimetry) of ice fraction dynamics during gradual cooling after inoculative freezing in variously acclimated larvae of two drosophilid flies, Drosophila melanogaster and Chymomyza costata Although the species and variants ranged broadly between 0 and close to 100% survival of freezing, there were relatively small differences in ice fraction dynamics. For instance, the maximum ice fraction (IFmax) ranged between 67.9% and 77.7% total body water (TBW). Chymomyza costata larvae showed statistically significant phenotypic shifts in parameters of ice fraction dynamics (melting point and IFmax) upon entry into diapause, cold acclimation and feeding on a proline-augmented diet. These differences were mostly driven by colligative effects of accumulated proline (ranging between 6 and 487 mmol kg-1 TBW) and other metabolites. Our data suggest that these colligative effects per se do not represent a sufficient mechanistic explanation for high freeze tolerance observed in diapausing, cold-acclimated C. costata larvae. Instead, we hypothesize that accumulated proline exerts its protective role via a combination of mechanisms. Specifically, we found a tight association between proline-induced stimulation of glass transition in partially frozen body liquids (vitrification) and survival of cryopreservation in liquid nitrogen.
- MeSH
- aklimatizace MeSH
- diferenciální skenovací kalorimetrie MeSH
- Drosophila melanogaster růst a vývoj fyziologie MeSH
- Drosophilidae růst a vývoj fyziologie MeSH
- larva fyziologie MeSH
- led * MeSH
- vitrifikace * MeSH
- zmrazování * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Non-isothermal differential scanning calorimetry was used to study the influences of particle size and mechanically induced defects on the recrystallization kinetics of amorphous Enzalutamide. Enzalutamide prepared by hot melt extrusion and spray-drying was used as a model material. The recrystallization rate was primarily accelerated by the presence of the processing-damaged surface of the powder particles. The actual surface/volume ratio associated with decreasing particle size fulfilled only a secondary role. Interestingly, higher quench rate during the extrusion led to a formation of thermally less stable material (with the worse stability being manifested via lower activation energy of crystal growth in the amorphous matrix). This can be the consequence of the formation of looser structure more prone to rearrangements. The recrystallization kinetics of the prepared Enzalutamide amorphous materials was described by the two-parameter autocatalytic kinetic model. The modified single-curve multivariate kinetic analysis (optimized for the data obtained at heating rate 0.5 °C•min-1) was used to calculate the extrapolated kinetic predictions of long-term isothermal crystal growth. The predictions were made for the temperatures from the range of drug shelf-life and processing for each particle size fraction. By the combination of the mass-weighted predictions for the individual powder fractions it was possible to obtain a very reasonable (temperature-extrapolated) prediction of the crystallization rate for the as-prepared unsieved powdered amorphous Enzalutamide.
