NPS received correspondence from Servier Laboratories (Australia) Pty Ltd in response to the RADAR article Strontium Ranelate for postmenopausal osteoporosis, published 1 October 2007. NPS's reply is underneath.

Servier correspondence

Servier would like to draw the attention of readers of NPS RADAR to the following commentary from the Therapeutics Committee of the Australian and New Zealand Bone & Mineral Society (ANZBMS)

“Strontium ranelate has been shown to reduce the risk of vertebral and non-vertebral fractures in two large trials, in patients with and without fractures at baseline, in postmenopausal women with osteoporosis or ostepenia and in women over 80 years of age. The ANZBMS notes that the effect size on non-vertebral fractures is comparable with the bisphosphonates. The drug reduces fractures within the first 12 months of the beginning of therapy and the benefits are sustained for 5 years. These features make it a first line option, not a second line agent to be used only after other therapy.”

This commentary was written in response to statements about strontium ranelate made by the NPS.

Servier agrees with the ANZBMS commentary and welcomes the decision of the PBS to allow usage of strontium ranelate (Protos) in postmenopausal women without a fracture (aged ≥ 70 years, BMD T-score ≤–3.0) as well as in postmenopausal women who have already suffered a minimal trauma fracture.

Strontium ranelate (Protos) has marketing approval for treatment of postmenopausal osteoporosis to reduce the risk of fracture. Servier does not suggest use the product in any way incompatible with that described in the Approved Product Information.

Date received: 15 November 2007.

NPS reply

The NPS RADAR review of strontium ranelate states that it may be used as initial therapy for postmenopausal osteoporosis. However, strontium has limited data for an effect on hip fracture, there is less experience of its use and its long-term safety profile is yet to be established. For these reasons, NPS RADAR and other independent reviews^1–3 have recommended strontium as an alternative therapy when alendronate or risedronate are contraindicated or not tolerated.

Evidence that strontium reduces hip fracture risk is limited to a post-hoc analysis of a high-risk subgroup of women (who were ≥ 74 years and had a BMD T-score ≤ –3.0) from the TROPOS trial.⁴ Statistically significant differences found in post-hoc subgroup analyses need to be interpreted with caution as they could be due to chance. Therefore the evidence that strontium reduces hip fracture risk is limited and requires confirmation. There are more robust data to support an effect of alendronate and risedronate on hip fracture risk in postmenopausal women with or without a previous fracture.^5–7 Refer to the NPS RADAR review for more information.

There are unpublished 5-year efficacy data for strontium.⁸ There are published data for up to 7 years with risedronate,⁹ and up to 10 years with alendronate.^10,11 As with any new drug, the full toxicity profile of strontium is yet to be established.

References

1. Stevenson M, Davis S, Lloyd-Jones M, et al. The clinical effectiveness and cost-effectiveness of strontium ranelate for the prevention of osteoporotic fragility fractures in postmenopausal women. Health Technology Assessment, Vol.11, No 4; executive summary. London, 2007. http://www.hta.nhsweb.nhs.uk/pdfexecs/summ1104.pdf (accessed 3 September 2007)
2. Anonymous. Strontium ranelate for osteoporosis? DTB 2006;44:29–32. [PubMed]
3. Anonymous. Strontium: postmenopausal osteoporosis: too many unknowns. Prescrire International 2005;14:207–11. [PubMed]
4. Reginster JY, Seeman E, De Vernejoul MC, et al. Strontium ranelate reduces the risk of nonvertebral fractures in postmenopausal women with osteoporosis: treatment of peripheral osteoporosis (TROPOS) study. J Clin Endorinol Metab 2005;90:2816–22 [PubMed]
5. Black DM, Cummings SR, Karpf DB, et al. Randomised trial of effect of alendronate on risk of fracture in women with existing vertebral fractures. Lancet 1996;348:1535–41. [PubMed]
6. Cummings SR, Black DM, Thompson DE, et al. Effect of alendronate on risk of fracture in women with low bone density but without vertebral fractures: results from the Fracture Intervention Trial. JAMA 1998;280:2077–82. [PubMed]
7. McClung MR, Geusens P, Miller PD, et al. Effect of risedronate on the risk of hip fracture in elderly women. Hip Intervention Program Study Group. N Engl J Med 2001;344:333–40. [PubMed]
8. Reginster JY, Meunier PJ, Roux C, et al. Strontium ranelate: an anti-osteoporotic treatment demonstrated vertebral and nonvertebral antifracture efficacy over 5 years in postmenopausal osteoporotic women. International Osteoporosis Foundation Osteoporosis International, 2006; 17 (Suppl 2): OC24.
9. Mellström DD, Sörensen OH, Goemaere S, et al. Seven years of treatment with risedronate in women with postmenopausal osteoporosis. Calcif Tissue Int 2004;75:462–8. [PubMed]
10. Black DM, Schwartz AV, Ensrud KE, et al. Effects of continuing or stopping alendronate after 5 years of treatment: the Fracture Intervention Trial Long-term Extension (FLEX): a randomized trial. JAMA 2006;296:2927–38. [PubMed]
11. Bone HG, Hosking D, Devogelaer JP, et al. Ten years' experience with alendronate for osteoporosis in postmenopausal women. N Engl J Med 2004;350:1189–99. [PubMed]