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Calcitonin Spray May Preserve Trabecular Bone Architecture


 

BETHESDA, MD. — Calcitonin nasal spray appears to preserve trabecular bone microarchitecture at the distal radius without substantially altering bone mineral density, Charles H. Chestnut III, M.D., reported during a meeting on bone quality.

In a 2-year, randomized, double-blind trial involving 91 women with an average age of 67 years, high-resolution MRI analysis of the distal radius showed that calcitonin nasal spray preserved significantly more trabecular bone architecture than placebo.

Calcitonin's effects included preservation of the volume, number, spacing, and thickness of trabecular bone, Dr. Chestnut wrote in a poster presentation at the meeting, which was sponsored by the National Institute for Arthritis and Musculoskeletal and Skin Diseases and the American Society for Bone and Mineral Research.

Trabecular bone microarchitecture was significantly preserved—if not reinforced—in calcitonin patients, compared with placebo patients, despite loss in bone mineral density (BMD) at the distal radius or lumbar spine during the same period, Dr. Chestnut said.

In placebo patients, the number of trabeculae declined slightly at those sites even if the women had gained BMD.

The results are consistent with earlier reports showing that calcitonin spray was associated with reductions in osteoporotic fractures in postmenopausal women with a history of vertebral fracture, despite producing minimal increases in BMD, said Dr. Chestnut, professor of medicine and radiology at the University of Washington, Seattle.

Almost none of the measurements of BMD in the lumbar spine or midradius were significantly correlated with measures of trabecular microarchitecture change as shown on high-resolution MRI, suggesting that “BMD is a poor marker for trabecular microarchitecture,” Dr. Chestnut wrote.

In the calcitonin group, trabecular microarchitecture in the lower trochanter was preserved, according to T2-MRI findings, regardless of whether patients lost or gained total hip BMD.

By comparison, trabecular microarchitecture deteriorated in the placebo group.

All women in the trial received calcium supplementation.

Dr. Chestnut reported that he has received research grants and consulting fees from Novartis Pharmaceuticals Corp., which funded the trial and manufactures calcitonin-salmon nasal spray, marketed as Miacalcin.

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