The role of modulated temperature differential scanning calorimetry in the characterisation of a drug molecule exhibiting polymorphic and glass forming tendencies

Bottom, R.

doi:10.1016/s0378-5173(99)00271-9

Cited by 31 publications

(9 citation statements)

References 7 publications

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“…While the presence of these two melting peaks was seen for each repeat measurement the reproducibility of their relative sizes was found to be poor. This had been noted previously for systems that had been recrystallized from the amorphous state during a DSC scan (Bottom 1999) and appears to be a common difficulty associated with such measurements. A small but reproducible discontinuity was also seen in the total and non-reversing signals at approximately 120-130mC, possibly representing a further solid-state process.…”

Section: Methodsmentioning

confidence: 59%

An investigation into the thermal behaviour of an amorphous drug using low frequency dielectric spectroscopy and modulated temperature differential scanning calorimetry

Craig

2001

Journal of Pharmacy and Pharmacology

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The objective of the study was to investigate the use of low frequency dielectric spectroscopy as a means of characterizing the thermal transitions of an amorphous drug substance, indometacin, with particular emphasis on modelling the response using the Dissado-Hill function. The low frequency dielectric behaviour of indometacin was measured over a temperature range of 10-160 degrees C and a frequency range of 10(-3)-10(6) Hz. Modulated temperature differential scanning calorimetry (MTDSC) studies were also performed on equivalent samples, showing a glass transition, recrystallization and melting. Isothermal low frequency dielectric spectra of the sample at temperatures below recrystallization showed the dynamic dielectric relaxation associated with the amorphous phase, while changes in the real and imaginary permittivities were observed that were associated with recrystallization and subsequent melting. A small discontinuity was observed immediately above the recrystallization process in the MTDSC and dielectric data, suggested to correspond to a solid state transformation. The use of the Dissado-Hill function as a means of modelling the dielectric behaviour has also been described. The study suggests that low frequency dielectric spectroscopy, used in conjunction with MTDSC and Dissado-Hill modelling, may be a useful tool for the characterization of amorphous and crystalline drugs.

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Section: Methodsmentioning

confidence: 59%

An investigation into the thermal behaviour of an amorphous drug using low frequency dielectric spectroscopy and modulated temperature differential scanning calorimetry

Craig

2001

Journal of Pharmacy and Pharmacology

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“…The DSC scan of CTAB showed three well-defined melting peaks, the first at 103.93°C, the second at 270°C, and the third at 295°C. According to Bottom,46 the presence of more than one melting point may indicate polymorphism.…”

Section: Resultsmentioning

confidence: 99%

Nanostructured lipid carriers for incorporation of copper(II) complexes to be used against <em>Mycobacterium tuberculosis</em>

Sato

Oshiro

Machado

et al. 2017

DDDT

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Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis. Cessation of treatment before the recommended conclusion may lead to the emergence of multidrug-resistant strains. The aim of this study was to develop nanostructured lipid carriers (NLCs) for use in the treatment of M. tuberculosis. The NLCs comprised the following lipid phase: 2.07% polyoxyethylene 40 stearate, 2.05% caprylic/capric triglyceride, and 0.88% polyoxyl 40 hydrogenated castor oil; the following aqueous phase: 3.50% poloxamer 407 (F1–F6), and 0.50% cetyltrimethylammonium bromide (F7–F12); and incorporated the copper(II) complexes [CuCl2(INH)2]·H2O (1), [Cu(NCS)2(INH)2]·5H2O (2), and [Cu(NCO)2(INH)2]·4H2O (3) to form compounds F11.1, F11.2, and F11.3, respectively. The mean diameter of F11, F11.1, F11.2, and F11.3 ranged from 111.27±21.86 to 134.25±22.72 nm, 90.27±12.97 to 116.46±9.17 nm, 112.4±10.22 to 149.3±15.82 nm, and 78.65±6.00 to 122.00±8.70 nm, respectively. The polydispersity index values for the NLCs ranged from 0.13±0.01 to 0.30±0.09. The NLCs showed significant changes in zeta potential, except for F11.2, with F11, F11.1, F11.2, and F11.3 ranging from 18.87±4.04 to 23.25±1.13 mV, 17.03±1.77 to 21.42±1.87 mV, 20.51±1.88 to 22.60±3.44 mV, and 17.80±1.96 to 25.25±7.78 mV, respectively. Atomic force microscopy confirmed the formation of nanoscale spherical particle dispersions by the NLCs. Differential scanning calorimetry determined the melting points of the constituents of the NLCs. The in vitro activity of copper(II) complex-loaded NLCs against M. tuberculosis H37Rv showed an improvement in the anti-TB activity of 55.4, 27.1, and 41.1 times the activity for complexes 1, 2, and 3, respectively. An in vivo acute toxicity study of complex-loaded NLCs demonstrated their reduced toxicity. The results suggest that NLCs may be a powerful tool to optimize the activity of copper(II) complexes against M. tuberculosis.

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“…The amount of free water is calculated from the enthalpy of the exothermic peak in the cooling scan or that of the endothermic peak in the re-heating scan after cooling by DSC (Ford 1999). The latter calculation method provides a more precise and more reproducible value than the former method (McCrystal et al 1999) because crystallization occurs via nucleation, which is an uncontrolled phenomena (Bottom 1999).…”

Section: Dsc Re-heating Scanmentioning

confidence: 99%

Thermal gelation of aqueous curdlan suspension: preparation of curdlan jelly

Hino

Ishimoto

Shimabayashi

2003

Journal of Pharmacy and Pharmacology

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Curdlan jelly was prepared by heating an aqueous curdlan suspension at 70 degrees C for 5 min. Theophylline, as a model drug, was entrapped in the jelly network. Curdlan jelly had a hardness comparable with that of commercially available jelly for confectionary. Syneresis was observed for 8 days after the preparation and was not detected during the experimental term from the gel prepared from 10% w/v curdlan suspension. Release of theophylline from the jellies was sustained, and was increasingly delayed with an increase in the curdlan concentration. An aqueous curdlan suspension was studied by means of differential scanning calorimetry (DSC) up to 80 degrees C and down to -25 degrees C, and subsequent re-heating to 30 degrees C. Enthalpy increased with the concentration of curdlan, while the temperature at the onset of the endothermic peak decreased with the concentration of curdlan. The enthalpy due to thermal gelation of 1 mg curdlan was 12.2 mJ. An increase in curdlan concentration decreased the enthalpy and lowered the onset temperature of the endothermic peak during the DSC re-heating scan. The results are due to an increase in the amount of non-freezing water and freezing bound water and a decrease in free water. The number of water molecules entrapped in the curdlan jelly as non-freezing water was 8.1 per glucopyranose residue.

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The role of modulated temperature differential scanning calorimetry in the characterisation of a drug molecule exhibiting polymorphic and glass forming tendencies

Cited by 31 publications

References 7 publications

An investigation into the thermal behaviour of an amorphous drug using low frequency dielectric spectroscopy and modulated temperature differential scanning calorimetry

An investigation into the thermal behaviour of an amorphous drug using low frequency dielectric spectroscopy and modulated temperature differential scanning calorimetry

Nanostructured lipid carriers for incorporation of copper(II) complexes to be used against <em>Mycobacterium tuberculosis</em>

Thermal gelation of aqueous curdlan suspension: preparation of curdlan jelly

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