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Calorimetry - Articles and news items

Isothermal calorimetry in the pharmaceutical sciences

Isothermal calorimetry in the pharmaceutical sciences

Issue 3 2013, Thermal Processing / 13 June 2013 / Anthony E. Beezer and Simon Gaisford, UCL School of Pharmacy

Fifty years ago, isothermal microcalorimetry (IMC) was a means to determine thermodynamic data (principally values for enthalpies of formation or reaction to assist in the calculation of Gibb’s Free Energy functions and entropies). These data were used in the compilation of tables of thermodynamic values, for use in evaluating, inter alia, reaction feasibilities, reaction extents (effectively equilibrium constants) and, indeed, reaction enthalpies. For these measurements, an experimental timescale of 30 minutes was considered long. The applications of IMC have developed and expanded considerably over the years, to the point where it can be considered a real-time process monitor with application to virtually all areas of pharmaceutical development. Accompanying this evolution has been a significant growth in the availability of commercial instruments (in contrast to the previous practice of individual, laboratory designed and built instruments).

Fast-scan differential scanning calorimetry

Issue 4 2008, Past issues / 2 August 2008 /

Differential scanning calorimetry (DSC) is a widely used technique within the pharmaceutical industry because the range of phase transitions it can measure usually allows near complete physical characterisation of a new active principal early during preformulation. In addition, because DSC measures a property change that is ubiquitous† (heat) there are very few samples that cannot be investigated.

Thermal analysis and calorimetry: latest developments

Issue 2 2008, Past issues / 19 March 2008 /

Thermal analysis techniques cover all methods in which a physical property is monitored as a function of temperature or time, whilst the sample is being heated or cooled under controlled conditions. Calorimetric methods measure the energy involved in every process. The quicker new developments attain the market, such as the progression of micro or nanotechnologies, combinations of different hyphenated techniques, as well as the development of high automated or high throughput systems, the faster new horizons will open in the industrial environment. In addition, the application of sophisticated kinetic software in DSC, calorimetry and reaction calorimetry gives better safety predictions.

Calorimetry for amorphous content quantification

Issue 3 2007 / 23 May 2007 / Simon Gaisford PhD and Rita Ramos PhD, School of Pharmacy, University of London

In the previous article (European Pharmaceutical Review, Issue 2, 2007) an introduction to calorimetry was given and its application to polymorph characterisation, discussed. Another area of application of growing importance is quantification of (usually small) amorphous contents. A requirement to demonstrate the presence or absence of amorphous material is becoming more important in regulatory documentation and calorimetric techniques are emerging as major tools in this arena. This article focuses on the use of various calorimetric techniques for quantifying amorphous content.

 

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