Physical characterization of dibasic calcium phosphate dihydrate and anhydrate

Tamaki Miyazaki, Kannan Sivaprakasam, Jaidev Tantry, Raj Suryanarayanan

Research output: Contribution to journalArticle

36 Scopus citations


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
Issue number3
StatePublished - Mar 2009


  • 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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