This is a review of the pharmacology of
strontium ranelate (
Protelos, Protos, Protaxos, Bivalos, Osseor), and its efficacy and tolerability in the treatment of patients with
postmenopausal osteoporosis.
Strontium ranelate is a divalent
strontium salt of ranelic
acid that is capable of increasing bone formation and reducing
bone resorption, thereby uncoupling and rebalancing bone turnover in favour of bone formation. The
drug is effective in reducing the risk of fractures, including both vertebral and nonvertebral fractures, in patients with
postmenopausal osteoporosis, according to data from two large, double-blind, placebo-controlled, multicentre trials of 5 years' duration, and reduced the risk of hip fracture in high-risk patients in a post hoc analysis of one trial. Moreover, data from patients who continued to receive the
drug during the 3-year extension phase of these trials indicate that
strontium ranelate continues to provide protection against new vertebral fractures and nonvertebral fractures for up to 8 years of
therapy. It also improves bone mineral density at numerous sites and both increases markers of bone formation and decreases markers of
bone resorption.
Strontium ranelate is administered orally as a
suspension and is generally well tolerated. The nature of adverse events was generally similar regardless of
treatment duration in clinical trials, with the most commonly reported being
nausea and diarrhoea over 5 years of treatment, and
memory loss and diarrhoea during longer-term treatment. Although an increased risk of
venous thromboembolism was associated with
strontium ranelate relative to placebo over 5 years of treatment in a pooled analysis of clinical trials, postmarketing data have not confirmed this finding. Overall, the clinical data available suggest that
strontium ranelate is an effective and generally well tolerated option for the first-line treatment of
postmenopausal osteoporosis.