Bisphosphonate (Bp) was adsorbed on the surface of crystalline calcium
phosphates (CP); hydroxyapatite (HAp), octacalcium phosphate (OCP) and
Dicalcium phosphate dehydrate (DCPD). The amount of Bp adsorbed was the
largest for DCPD per unit surface area, while the amount was the largest for
HAp per unit weight. The composites of Bp and amorphous calcium phosphate
(ACP) were synthesized by titrating calcium acetate solution into phosphate
buffer solution containing Bp. The amount of Bp doped in the composites was
366 μg / mg and was approximately 7 times larger than those of Bp adsorbed
on the crystalline Calcium phosphates. TG-DTA measurements of a Bp-calcium
and the composite indicated exothermic peaks due to Bp combustion, of which
temperature were shifted to higher temperature for the composite. Bp in the
composites was gradually released into phosphate buffered saline, while Bp
was rapidly released into acetate buffer solution accompanied with the
dissolution of ACP. This result suggests that the composite of Bp and ACP
has potential for a drug-carrier releasing Bp in response to the condition
of osteoclastic bone resorption.