Physical characterization of dibasic calcium phosphate dihydrate and anhydrate

Tamaki Miyazaki, Kannan Sivaprakasam, Jaidev Tantry, Raj Suryanarayanan

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

The dehydration of different commercial brands of dibasic calcium phosphate dihydrate (DCPD; CaHPO4·2H2O) was examined over a range of temperatures and water vapor pressures. To determine the main factors affecting the physical stability of DCPD, the baseline characterization of DCPD and dibasic calcium phosphate anhydrate (DCPA; CaHPO4) was conducted by thermogravimetric analysis, differential scanning calorimetry and X-ray diffractometry. The surface area and the DCPA content (present as an impurity) depended on the commercial source of DCPD. The larger particles contained a higher concentration of DCPA and the anhydrate exhibited a concentration- dependent acceleratory effect on the dehydration of DCPD. Unlike DCPD, DCPA is physically stable and resisted hydration even when dispersed in water for over 7 months in the temperature range of 4-50°C. In dosage forms containing DCPD, there is a potential for phase transformation to DCPA, while the reverse transition, that is, DCPA → DCPD appears to be extremely unlikely. Thus, the risk of physical transformation can be minimized by using DCPA in formulations.

Original languageEnglish (US)
Pages (from-to)905-916
Number of pages12
JournalJournal of Pharmaceutical Sciences
Volume98
Issue number3
DOIs
StatePublished - Mar 2009

Bibliographical note

Funding Information:
We gratefully acknowledge the financial support from Dane O. Kildsig Center for Pharmaceutical Processing Research. Part of this work was carried out in the University of Minnesota I.T. Characterization Facility, which receives partial support from NSF through the NNIN program.

Keywords

  • Amorphous
  • Calorimetry (DSC)
  • Dehydration
  • Dibasic calcium phosphate
  • Particle size
  • Physical characterization
  • Physical stability
  • Thermal analysis
  • Water in solids
  • X-ray diffractometry

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