Controlled release of aminomethylenebisphosphonates from a calcium zeolite carrier: investigating the impact of compound structure on sorption and release profiles†

Abstract

This study investigates the controlled release of the aminomethylenebisphosphonates from a calcium-exchanged zeolite carrier and explores the influence of compound structure on sorption and release profiles. Thirteen bisphosphonates (BPs), including risedronate (RSD), were tested for their sorption capacity and release behavior in simulated body fluid (SBF). Sorption studies revealed that BPs with iodine, methyl, and benziothiazole groups (BP5, BP6, and BP12) exhibited high sorption rates (>50%), while compounds containing bromine or chlorine displayed lower sorption capacities. Release experiments demonstrated that RSD, BP5, and BP6 followed a sustained release profile, while BP12 showed an initial burst followed by a tapering release. The density functional theory (DFT) calculations provided further insight into the adsorption mechanisms, highlighting the role of dispersion interactions and electrostatic bonding with calcium ions. The use of zeolite carriers reduced the toxicity of drugs towards human fibroblast BJ cells. The effect of the carrier addition on osteosarcoma 143b cells was also determined; some of the drugs did not lose their activity in relation to them after being placed on the carrier. These findings suggest that calcium-exchanged zeolite carriers can effectively facilitate the controlled release of BPs, offering potential for applications in osteoporosis treatment by maintaining therapeutic levels over extended periods.