title: Differences between bisphosphonates in binding affinities for hydroxyapatite.
abstract: Bisphosphonates (BPs) inhibit bone resorption and are widely used for the treatment of bone diseases, including osteoporosis. BPs are also being studied for their effects on hydroxyapatite (HAP)-containing biomaterials. There is a growing appreciation that there are hitherto unexpected differences among BPs in their mineral binding affinities that affect their pharmacological and biological properties. To study these differences, we have developed a method based on fast performance liquid chromatography using columns of HAP to which BPs and other phosphate-containing compounds can adsorb and be eluted by using phosphate buffer gradients at pH 6.8. The individual compounds emerge as discrete and reproducible peaks for a range of compounds with different affinities. For example, the peak retention times (min; mean +/- SEM) were 22.0 +/- 0.3 for zoledronate, 16.16 +/- 0.44 for risedronate, and 9.0 +/- 0.28 for its phosphonocarboxylate analog, NE10790. These results suggest that there are substantial differences among BPs in their binding to HAP. These differences may be exploited in the development of biomaterials and may also partly explain the extent of their relative skeletal retention and persistence of biological effects observed in both animal and clinical studies.
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology & Musculoskeletal Sciences, The Oxford University Institute of Musculoskeletal Sciences, Oxford, UK.
authors.forename: M A
authors.initials: MA
authors.lastname: Lawson
authors.forename: Z
authors.initials: Z
authors.lastname: Xia
authors.forename: B L
authors.initials: BL
authors.lastname: Barnett
authors.forename: J T
authors.initials: JT
authors.lastname: Triffitt
authors.forename: R J
authors.initials: RJ
authors.lastname: Phipps
authors.forename: J E
authors.initials: JE
authors.lastname: Dunford
authors.forename: R M
authors.initials: RM
authors.lastname: Locklin
authors.forename: F H
authors.initials: FH
authors.lastname: Ebetino
authors.forename: R G G
authors.initials: RG
authors.lastname: Russell
mesh_terms: D050071:Bone Density Conservation Agents / Q000737:chemistry*; D002853:Chromatography, Liquid; D004164:Diphosphonates / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D012968:Etidronic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry*; D000068296:Risedronic Acid; D013056:Spectrophotometry, Ultraviolet; D000077211:Zoledronic Acid
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D007093:Imidazoles; D000077211:Zoledronic Acid; D017886:Durapatite; D000068296:Risedronic Acid; D012968:Etidronic Acid