Adsorption and irreversible binding of adriamycin incorporated into hydroxyapatite beads

Adriamycin-loaded porous hydroxyapatite (HAP) beads were investigated in terms of drug adsorption and drug release from solution-loaded wet beads and the corresponding dry beads. The wet beads resulted in almost 100% release of the drug into water while the dry beads released only about 60%. A possible explanation for this observation is that direct contact between the drug and the surface of HAP in the dry state induced strong irreversible binding through electrostatic forces and hydrogen bond and/or complex formation with surface calcium.