Physical characterization of dibasic calcium phosphate dihydrate and anhydrate

✍ Scribed by Tamaki Miyazaki; Kannan Sivaprakasam; Jaidev Tantry; Raj Suryanarayanan

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 380 KB
• Volume: 98
• Category: Article
• ISSN: 0022-3549
• DOI: 10.1002/jps.21443

✦ Synopsis

The dehydration of different commercial brands of dibasic calcium phosphate dihydrate (DCPD; CaHPO 4 Á2H 2 O) 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; CaHPO 4 ) 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 4-508C. 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.