Strontium ranelate: a novel treatment for postmenopausal osteoporosis: a review of safety and efficacy

Abstract

Strontium ranelate is a new orally administered agent for the treatment of women with postmenopausal osteoporosis that reduces the risk of vertebral and hip fractures. Evidence for the safety and efficacy of strontium ranelate comes from two large multinational trials, the SOTI (Spinal Osteoporosis Therapeutic Intervention) and TROPOS (Treatment Of Postmenopausal Osteoporosis) studies. The SOTI study evaluated vertebral fracture prevention in 1649 postmenopausal women with a mean age of 69 y. The subjects all had at least one previous vertebral fracture and a low spine bone mineral density (BMD) (equivalent to a Hologic spine T-score below -1.9). The strontium ranelate group had a 41% lower risk of a new vertebral fracture than the placebo group over the three-year study period (relative risk [RR] = 0.59; 95% confidence interval [CI]: 0.48-0.73; p < 0.001). The TROPOS study evaluated non-vertebral fracture prevention in 5091 postmenopausal women with a mean age of 77 y. The subjects were aged 74 y and over (or 70-74 y with one additional risk factor) and a low femoral neck BMD (equivalent to an NHANES III [Third National Health and Nutrition Examination Survey] T-score below -2.2). Over the three-year study period there was a 16% reduction in all non-vertebral fractures (RR = 0.84; 95% CI 0.702-0.995; p = 0.04) and a 19% reduction at the principal sites for non-vertebral fractures. The TROPOS study was not powered to investigate hip fracture risk. However, in a high risk group of women aged 74 y and over and with an NHANES III femoral neck T-score less than -2.4 there was a 36% reduction in hip fracture risk (RR = 0.64; 95% CI: 0.412-0.997; p = 0.046). The overall incidence of adverse events did not differ significantly from placebo and were generally mild and transient, the most common being nausea and diarrhea. Strontium ranelate is a useful addition to the range of anti-fracture treatments available for treating postmenopausal women with osteoporosis and is the only treatment proven to be effective at preventing both vertebral and hip fractures in women aged 80 y and over.

Figure 1

Chemical structure of strontium ranelate (Marie et al 1993).

Figure 2

Results for vertebral fracture reduction by strontium ranelate treatment in the SOTI and TROPOS studies (Meunier et al 2004; Reginster et al 2005, 2006). Results are shown as the relative risk (RR) and 95% confidence intervals. Abbreviations: SOTI, Spinal Osteoporosis Therapeutic Intervention; TROPOS, Treatment Of Postmenopausal Osteoporosis.

Figure 3

Results for non-vertebral fracture reduction by strontium ranelate in the TROPOS study (Reginster et al 2005, 2006). Results are shown as the relative risk (RR) and 95% confidence intervals. Abbreviations: TROPOS, Treatment Of Postmenopausal Osteoporosis.

Figure 4

(A) Data from the SOTI study (Meunier et al 2004) showing the effect of 3 years treatment with strontium ranelate (2 g/day) on spine bone mineral density (BMD). The BMD values have not been adjusted for the bone strontium content. (B) Mean percentage changes in spine BMD from baseline to 3 years in patients receiving active treatment in four clinical trials: (i) raloxifene (60 mg/day) (Ettinger et al 1999); (ii) risedronate (5 mg/day) (Harris et al 1999); (iii) alendronate (10mg/day) (Liberman et al 1995); (iv) hPTH(1–34) and oestrogen (Lindsay et al 1997). Abbreviations: hPTH, Human recombinant parathyroid hormone; SOTI, Spinal Osteoporosis Therapeutic Intervention.