Energetic yields in apatitic calcium phosphate compression: influence of the Ca/P molar ratio

Abstract

AbstractThe chemical nature of tricalcium phosphate used as compression excipient is not well defined. It can vary between β‐tricalcium phosphate (Ca/P molar ratio = 1.50) and hydroxyapatite (Ca/P molar ratio = 1.67). The present study deals with the compression properties of calcium phosphates with different Ca/P molar ratios (1.50, 1.63 and 1.67) and two trading excipients elaborated by different manufacturing processes: TRI‐TAB® (granulated powder) and TRI‐CAFOS S® (spray‐dried powder). The compression properties are analyzed in terms of energetic compression yields deduced from the compression and rupture cycles. The results show that the proportions of friction and elasticity during apatitic calcium phosphate compression are the same, whatever the chemical nature and the manufacturing process of the material. The only property that differs greatly is the conversion of the energy into cohesion. In comparison with trading excipients, the synthesized apatitic calcium phosphate materials exhibit higher cohesion properties: the product with a Ca/P molar ratio of 1.63 is the most cohesive, the apatitic tricalcium phosphate converts to a smaller extent the compression energy into cohesion, whereas hydroxyapatite displays a similar compression ability as TRI‐TAB and TRI‐CAFOS S. This study shows the importance of the chemical nature on the compression properties of apatitic calcium phosphates, and the need to rationalize the physical grade as well as the chemistry of the commercialized materials. The elaboration process does not seem to influence the efficiency of the cohesion acquisition, but affects the flowability.© 2003 Society of Chemical Industry