title: Oral ibandronate in postmenopausal osteoporotic women alters micromechanical properties independently of changes in mineralization.
abstract: Postmenopausal osteoporotic (PMOP) women treated with ibandronate had higher bone mineral density, lower bone turnover, and decreased incidence of new vertebral fractures. The aim of this study was to investigate the effect of daily or intermittent oral ibandronate on the degree of mineralization (DMB) of bone and microhardness (Hv) at the bone tissue and bone structural unit (BSU) levels. A total of 110 iliac biopsies were taken from patients treated for 22 or 34 months with an oral placebo (n = 36), 2.5 mg daily oral ibandronate (n = 40), or 20 mg intermittent oral ibandronate (n = 34). These regimens provide annual cumulative exposures (ACEs) that are about half of the therapeutic doses currently licensed for PMOP women. DMB and Hv were measured at the global level (i.e., cortical or cancellous) and the focal level (i.e., BSU). At the global level, DMB and its distribution were not significantly different from placebo after 22 and 34 months of treatment. Hv was significantly higher in the cortical, cancellous, and total bone after 22 and 34 months of ibandronate versus placebo for both regimens. At the focal level, DMB and Hv, measured simultaneously in 3,760 BSUs, were significantly and positively correlated in all groups (r = 0.59-0.65, p < 0.0001). However, analysis of covariance highlighted the differences in the y intercepts of the linear regressions of the placebo- and ibandronate-treated groups. We infer that a low ACE of oral ibandronate altered the bone micromechanical properties irrespective of changes in secondary mineralization.
authors.affiliation: INSERM UMR 1033 Equipe Qualité Osseuse et Marqueurs Biologiques, Faculté de Médecine Lyon Est, Claude Bernard (Domaine Laennec), Université de Lyon, 7-11 rue Guillaume Paradin, 69372, Lyon Cedex 08, France. yohannbala@gmail.com
authors.forename: Yohann
authors.initials: Y
authors.lastname: Bala
authors.forename: Joseph
authors.initials: J
authors.lastname: Kohles
authors.forename: Robert R
authors.initials: RR
authors.lastname: Recker
authors.forename: Georges
authors.initials: G
authors.lastname: Boivin
mesh_terms: D000284:Administration, Oral; D000368:Aged; D001706:Biopsy / Q000379:methods; D015519:Bone Density / Q000187:drug effects; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D004164:Diphosphonates / Q000627:therapeutic use*; D004311:Double-Blind Method; D005260:Female; D050723:Fractures, Bone / Q000517:prevention & control; D006801:Humans; D000077557:Ibandronic Acid; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000188:drug therapy*; D010919:Placebos; D012044:Regression Analysis; D015203:Reproducibility of Results; D016896:Treatment Outcome
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D010919:Placebos; D000077557:Ibandronic Acid