A team of researchers say that women with low bone density can benefit from a twice a year treatment of an experimental drug.
They say the drug denosumab injected twice a year can strengthen the density of bones in the spine.
The results come at the end of the first year of study, some three months after Amgen reported on the effects of the drugs following two years of use as part of the same study.
The volunteers, who were 412 women with low bone density, were randomly assigned to receive the drug either every three months (at a dose of 6, 14, or 30 mg) or every six months (at a dose of 14, 60, 100, or 210 mg), open-label oral alendronate once weekly (at a dose of 70 mg), or a placebo.
The researchers found by carrying out bone density tests after one year of treatment, denosumab was found to increase bone density at the lumbar portion of the spine from 3 to 6.7 percent and density measurements in other bones also improved.
At the two year point in November, the company announced that the increase ranged from 4.3 percent to 9.0 percent.
These results are comparable to those seen for Fosamax, which produced a 4.6 percent increase at the one-year point, when volunteers who received a placebo lost bone in the spine.
Drug company Amgen funded, designed and holds the data for the study and also conducted the statistical analysis.
The company says no serious side effects were reported.
Denosumab at present appears to have an advantage in that it persists in the body.
As research has shown that only about one in four women given drugs to prevent osteoporosis actually take them regularly, a drug that only needs to be taken two or four times a year will be welcomed by doctors. Fosamax is taken once a week.
The research team, led by Michael McClung of the Providence Portland Medical Center in Portland, Oregon, found that the best result were achieved among women who received a 60 milligram injection of denosumab once every six months.
About 10 million Americans have osteoporosis, and four out of five are women.
The research is published in the New England Journal of Medicine.