Strontium ranelate: a novel treatment in postmenopausal osteoporosis

Strontium ranelate (SR) is a novel antiosteoporotic agent, electively concentrated in positions of active bone formation, and especially onto the crystal surface that allows permanent exchanges with extracellular fluid. Although the mechanism(s) of action is still under rigorous research, SR appears to reduce bone resorption by decreasing osteoclast differentiation and activity and to stimulate bone formation by increasing replication of preosteoblast cells, leading to increased matrix synthesis. In the placebo-controlled, phase III trial spinal osteoporosis therapeutic intervention (SOTI) (no=1442; mean age 69 years), there was a 41% decrease over 3 years in the number of patients with new vertebral fractures in the SR (2 g/day) group versus placebo (P<0.001), already detected after 12 months (49% lower risk, P<0.001). The phase III treatment of peripheral osteoporosis (TROPOS) study assessed the efficacy of SR (2 g/day) in preventing nonvertebral fractures in postmenopausal osteoporosis (no=4932; mean age 77 years). SR reduced nonvertebral fracture risk by 16% versus placebo (P=0.04) and hip fracture risk by 36% (P=0.031) in osteoporotic patients older than 74 years. Thus SR is an effective and safe treatment for vertebral and hip osteoporosis with a unique mode of action.