A review on strontium ranelate long-term antifracture efficacy in the treatment of postmenopausal osteoporosis

Osteoporotic fractures are one of the major causes of increased morbidity and mortality in postmenopausal women and the overall aging population. One of the major issues in the management of postmenopausal osteoporosis is to find a safe and effective treatment in the long term (>3 years) to achieve and maintain a reduction in the risk of fracture. Strontium ranelate (PROTELOS (R)) is a relatively novel drug, currently approved in Europe for the treatment of postmenopausal osteoporosis. Strontium ranelate is the first agent of a new therapeutic class in osteoporosis, capable of both promoting bone formation and, to a lesser extent, inhibiting bone resorption. This uncoupling in bone turnover results in a net gain in bone mineral density (BMD), bone quality improvement and reduction in risk of vertebral and nonvertebral fractures, as initially demonstrated in the preplanned long-term registrative trials SOTI (Spinal Osteoporosis Therapeutic Intervention) and TROPOS (Treatment of Peripheral Osteoporosis) at 5 years. Recently, open-label extensions of the SOTI and TROPOS trials up to 8 and, recently, 10 years have confirmed the sustained efficacy of strontium ranelate in increasing BMD, the long-term safety profile and the high compliance to treatment, independently from baseline BMD or other risk factors for osteoporotic fractures. Recent economic impact analyses have proved that long-term treatment with strontium ranelate is highly cost effective, especially in women older than 70 years of age. Histomorphometric analyses in animals and humans participating in the phase III trials have proved that the quality of mineralization is preserved in the long term and bone microarchitecture is ameliorated, with increased bone strength. Thus, strontium ranelate has been confirmed to be an effective compound for the long-term, chronic treatment of postmenopausal osteoporosis.