New bone can be formed by a regimen that includes taking a hormone followed by a prescription drug for extended periods of time, scientists say. The discovery could lead to fewer fractures, particularly in people who have osteoporosis, the University of California-San Francisco researchers contend.

Bone density in the spines of study subjects who took a hormone similar to Forteo, an FDA-approved bone builder, followed by a year on Fosamax, a drug taken to prevent bone-density loss, increased 12%. More than 230 women in four cities took part in the study, which was featured in a recent edition of the New England Journal of Medicine.

Researchers urged physicians and patients to try the regimen. But they also cautioned that the positive effects of the expensive bone-building agent seemed to be wiped out if nothing was done the following year.

Taking Forteo (parathyroid hormone) followed by Fosamax “is clearly an effective” treatment, said Dr. Felicia Cosman, clinical director of the Osteoporosis Foundation. She reached similar findings in a similar study that was also noted in the new England Journal of Medicine. Cosman predicted the findings would “make a very big difference to people who have very severe disease,” according to published reports.