Interpretation of BMD Scans in Patients Stopping Strontium Ranelate Treatment

“The oral administration of strontium ranelate causes a clinically significant overestimation of BMD because of the high attenuation of X-rays by strontium atoms in bone." GM Blake and I. Fogelman “performed a theoretical study to calculate the long-term effect of strontium treatment on BMD and establish the duration of past treatment for which the remaining bone strontium content (BSC) has a negligible effect on BMD.” “Estimates of the strontium BMD artefact after treatment has stopped were performed on the assumption that the BSC effect accounts for 75% of the total measured BMD change at 3 years.” “If 75% of the BMD changes are explained by BSC, in the average patient, 3-year treatment leads to a spine BMD artefact of 11.2%, decreasing to 3.8% 10 years after stopping treatment. The BMD artefacts at the total hip and femoral neck sites are smaller by factors of 0.65 and 0.53, respectively.” “On average, 6-month treatment is required for the spine BMD artefact to exceed 3%, the figure adopted as the maximum BMD change caused by bone strontium that has a negligible effect on scan interpretation.” The researchers concluded that “strontium ranelate treatment lasting for > 6 months can affect BMD measurements for many years afterward.” http://www.ncbi.nlm.nih.gov/pubmed/16939400 J Bone Miner Res. 2006 Sep;21(9):1417-24.

Minimum Effective Doses of Strontium

The aim of the PREVOS study (PREVention Of early postmenopausal bone loss by Strontium ranelate) and the STRATOS study (STRontium Administration for Treatment of OSteoporosis) was to determine the minimum dose at which strontium ranelate (SR) is effective in, respectively, the prevention of bone loss in early postmenopausal nonosteoporotic women and the treatment of postmenopausal vertebral osteoporosis.

The minimum dose at which SR is effective in preventing bone loss in early postmenopausal nonosteoporotic women and in the treatment of postmenopausal osteoporosis is 1 g/day and 2 g/day, respectively.

Strontium ranelate phase 2 dose-ranging studies: PREVOS and STRATOS studies, J. Y. Reginster and P. J. Meunier, Osteoporosis International, Volume 14, Supplement 3, 56-65, DOI: 10.1007/s00198-002-1349-0

The chemical structure of strontium ranelate is composed of two atoms of stable strontium combined with organic ranelic acid. Strontium is the bone active component and makes up 34% by weight of the whole molecule, so each 2 g dose of strontium ranelate delivers 680 mg of elemental strontium.

 Strontium ranelate: a novel treatment for postmenopausal osteoporosis: a review of safety and efficacy, Glen M Blake and Ignac Fogelman, Clinical Interventions in Aging, Dec. 2006, 1(4): 367-375

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2699648/