Good to the Bone: Strontium compound prevents some fractures

An experimental drug containing strontium makes bones denser and decreases the risk of fractures, a study of elderly women finds. The results add the drug, called strontium ranelate, to a wave of new treatments for osteoporosis.

Strontium, a soft metal with chemical similarities to calcium, is widely dispersed in nature. In the 1950s, strontium emerged as a potential osteoporosis drug because it shows a natural attraction to bone. But researchers soon shelved that approach. Strontium was later used as a treatment for bone cancer pain.

Recently, researchers combined strontium with ranelic acid to produce the experimental drug. It aided bone growth and boosted bone density in animal studies and lessened fractures in preliminary tests in people.

In the new study, between 1996 and 1998, researchers identified 1,442 postmenopausal women, average age 69, who had osteoporosis. The women all began taking vitamin D and calcium supplements. Half also received 2 grams of strontium ranelate powder daily. The others got an inert powder as a placebo.

During the 3-year test period, 21 percent of the women taking strontium ranelate suffered a vertebral fracture, compared with 33 percent of those getting the placebo, physician Pierre J. Meunier of the Édouard Herriot Hospital in Lyon, France, and his colleagues report in the Jan. 29 New England Journal of Medicine.

The two groups of women had begun the study with similar bone density. After 3 years of participation, those getting the placebo had a 1.3 percent density decline in the lower vertebrae. In contrast, women receiving strontium ranelate showed a density increase of 6.8 percent in that area. The drug’s only side effect was temporary diarrhea in a small percentage of volunteers.

“This is really beautiful work. It’s very thorough,” says Agnès Vignery, a molecular biologist at Yale University. “This drug should be used,” she says.

The new study establishes the efficacy of strontium ranelate for osteoporosis, agrees Ghada El-Hajj Fuleihan, a physician at the American University of Beirut Medical Center in Lebanon, in an editorial in the same issue.

However, the antifracture effect of strontium ranelate doesn’t appear to be as dramatic as that of some other drugs, says Felicia Cosman, clinical director for the National Osteoporosis Foundation in Washington, D.C., and a physician at Helen Hayes Hospital in West Haverstraw, N.Y. “I’m happy the drug works for vertebral fractures,” she says, “but I’m not enthusiastic about the fact that it doesn’t appear to be better than standard antiresorptive drugs.” Antiresorptive drugs work by suppressing bone erosion.

To stay healthy, bone needs to be constantly dissolved and replaced with new bone, Vignery explains. By aiding this remodeling process, rather than simply inhibiting bone loss, strontium ranelate and an injected form of parathyroid hormone have an edge over antiresorptive drugs, she says. Estrogen also spurs remodeling, but it may create other health problems (SN: 5/31/03, p. 341: Available to subscribers at Flawed Therapy: Hormone replacement takes more hits).

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