Journal of Thermal Analysis and Calorimetry

, Volume 78, Issue 1, pp 47–54 | Cite as

Use of isothermal microcalorimetry in pharmaceutical preformulation studies, Part I. Monitoring crystalline phase transitions

  • N. Murti Vemuri
  • Zofia Chrzan
  • Raghu Cavatur


Solid-state transformation kinetics of two crystal forms of a synthetic tetrapeptide was monitored by isothermal microcalorimetry and complementary solid-state analytical techniques. Form B, the crystal form obtained from the synthetic process transformed to Form D upon exposure to higher relative humidity conditions (>60% RH). The transformation occurred rapidly at higher temperature, and relative humidities. An intermediate phase of very low crystallinity (amorphous-like phase) was observed when transformation was slow. Form D was observed to be physically stable at higher relative humidities and thus the preferred crystal form for development. Exposure of Form B to high relative humidity was the only process through which Form D was obtained. Optimal conditions for transformation of Form B to Form D were determined by microcalorimetric experiments and were used for larger scale processing of Form B to Form D.

crystallization microcalorimetry polymorphism amorphous solid-state transformation 


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Copyright information

© Kluwer Academic Publisher/Akadémiai Kiadó 2004

Authors and Affiliations

  • N. Murti Vemuri
    • 1
  • Zofia Chrzan
    • 1
  • Raghu Cavatur
    • 1
  1. 1.Aventis Pharmaceuticals Route 202-206 SUSA E-mail

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