The study disproved a previously untested but widespread belief among bone researchers that combining the two types of drugs -- bone-building parathyroid hormone (PTH) and bone resorption inhibiting bisphosphonates -- should interact in a beneficial way for patients. The combination is no better than either drug alone and may even reduce the bone-building benefit, according to study results.
Black presented the findings at the American Society for Bone and Mineral Research in Minneapolis on September 20. The study results are also reported in the September 25 issue of the New England Journal of Medicine.
The randomized, double-blind trial measured the bone density of 238 postmenopausal women for one year as they took one of three daily treatments. Participants in the multi-site study took either parathyroid hormone (PTH 1-84); the bisphosphonate alendronate, marketed as Fosamax; or both. All the women began the trial with low bone mineral density.
Parathyroid hormone in the form of PTH 1-34 has been available for treatment of severe osteoporosis since its FDA approval in 2002. This trial evaluated the full-length molecule PTH 1-84 that contains 50 additional amino acids. Despite a wide-spread belief among bone researchers that bisphosphonates and parathyroid hormone would interact in a synergistic way to compound the benefit for patients, no benefit was demonstrated. Rather, the findings suggest that the concurrent use of alendronate may reduce the bone-building, or anabolic, effects of parathyroid hormone.
"We're in the early stages of use for a whole new class of bone-building medications for osteoporosis," said UCSF Professor Dennis Black, PhD, principal investigator. "These anabolic agents offer an alternative, and, with decreased reliance on estrogen,
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Contact: Eve Harris
eharris@pubaff.ucsf.edu
415-885-7277
University of California - San Francisco
20-Sep-2003