Hydroxyapatite–alendronate composite systems for biocompatible materials

In this study, hydroxyapatite–alendronate composites were synthesized from calcium nitrate, diammonium hydrogen phosphate and alendronate by chemical precipitation method. The obtained materials were analysed by physical–chemical methods, while the compositional and structural characteristics of hydroxyapatite–alendronate phases were determined by a combination of crystallographic, spectroscopic and thermal analysis investigations; moreover, the alendronate content, its maximal incorporation efficiency to hydroxyapatite and stability were determined. A two-level full factorial design was chosen to determine the optimum set of process parameters (synthesis temperature, reactant addition rate and ripening time) and their effects on various hydroxyapatite–alendronate characteristics: alendronate incorporation efficiency, hydroxyapatite crystallite size (XRD), hydroxyapatite particle size distribution (DLS). These effects were quantified using design of experiments. The in vitro release profile of alendronate from hydroxyapatite–alendronate tablets was assessed.