Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.1.2.42 (DTA)
 1,693 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The use of microthermal analysis as a novel means of assessing chemical incompatibility between drugs and excipients is assessed using magnesium stearate and acetylsalicylic acid as a model system. Localised thermomechanical analysis (L-TMA), localised differential thermal analysis (L-DTA), nanosampling, thermally assisted particle manipulation (TAPM) and photothermal microspectrometry (PTMS) are developed as a means of allowing extremely small quantities of drug and excipient to be heated in close proximity to each other. Differential scanning calorimetry (DSC), hot stage microscopy (HSM) and temperature controlled attenuated total internal reflection (ATR) FTIR were used as supportive techniques. L-TMA and macroscopic TMA of magnesium stearate indicated that the endothermic DSC peak normally associated with melting does not correspond to significant liquefaction. An optimised method for detecting the interaction at a particulate level of scrutiny was developed whereby the drug is placed on the excipient surface via TAPM and the construct heated, allowing the interaction to be detected in both the L-TMA and L-DTA signal. PTMS allowed spectra to be obtained on nanogram-sized samples and also allowed the interaction to be detected. The study has therefore demonstrated the potential for using TAPM with PTMS for studying interactions at an individual particle level.
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PMID:The development of microthermal analysis and photothermal microspectroscopy as novel approaches to drug-excipient compatibility studies. 1816 42

We have synthesised and characterised a novel organic-inorganic hybrid crystal, [(CH3)2NH2]2KCr(CN)6. The thermal DSC, TMA, DTG and DTA analyses indicate two solid-to-solid structural phase transitions (PTs). According to the X-ray diffraction experiments, the first PT at 220 K is isostructural, since it does not involve a change of the space group. This transition occurs between the states, where the (CH3)2NH2+ cations are orientationally disordered and ordered (frozen). The other reversible PT at 481 K leads to a melt-like phase similar to the one observed in plastic crystals or polar liquids. Dielectric spectroscopy has been used to characterise the switching properties of the dipole moments in the vicinity of the PTs. Continuous-wave electron paramagnetic resonance spectroscopy was employed to investigate the effect of ordering on the local environment of the Cr3+ ions. We have also applied the quasielastic neutron scattering (QENS) technique as well as 1H NMR spectroscopy to measure the dynamics of the (CH3)2NH2+ cations residing in the inorganic framework.
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PMID:Isostructural phase transition, quasielastic neutron scattering and magnetic resonance studies of a bistable dielectric ion-pair crystal [(CH3)2NH2]2KCr(CN)6. 3082 2