Dr. Recker points out that effect is misleading because the mineral is denser than the calcium normally found in the skeleton. "It's hard to tell if there's an actual increase in bone," in the patient, says Dr. Recker, who is doubtful the medication will gain approval for use in the U.S.

Interestingly, an American-based company, Osteologix, recently announced favorable results in a clinical trial for its investigational drug strontium malonate, known as NB S101. Like Protelos, NB S101 also incorporates strontium, but it is used with malonic acid rather than the ranelic acid of the European medication. The studies indicated the Osteologix drug increased bone mineral density in the lumbar spine, at levels about equivalent to strontium ranelate. In addition, the drug helped patients reduce CTX-1, a biomarker associated with bone resorption activity, at greater levels than those taking Protelos. Unlike the powder form of the European drug, however, strontium malonate is being formulated as a tablet to be taken once daily.