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The research, reported at the annual meeting of the American Society for Bone and Mineral Research in Toronto, suggests that the drug may spur growth in a damaged jaw, the researchers said.
Forteo (Parathroid Hormone), known generically as teriparatide, cuts in half the risk of bone fractures in patients with thinning bones by stimulating the growth of new bone. But it is seldom given for more than two years out of fear that long-term exposure might lead to osteosarcoma, a type of bone cancer.
Forteo is a man-made (well, E. coli-made) recombinant parathyroid hormone that has an amino acid sequence identical to part of the human parathyroid hormone (PTH). Forteo was approved by the US FDA in 2001 as an osteoporosis drug.
10 times more bone
The first of two reports, also published in the New England Journal of Medicine, showed people whose severe periodontitis was damaging the tissue around the teeth developed nearly 10 times more bone with Forteo compared to those who received daily placebo injections.
"There was a significant gain in the bone around the teeth as measured by X-rays," Dr Laurie McCauley of the University of Michigan said in a telephone interview. "This relatively short dosing period of six weeks resulted in improvements that were sustained, and things actually improved over 12 months."
The 40 volunteers were also treated with periodontal surgery as part of the test, which was financed by Eli Lilly and company, which makes Forteo. Periodontitis is a major cause of tooth loss, affecting more than one in five US adults. "We were very pleased with these results and we're looking at other approaches," McCauley said.
"One is trying to administer the drug locally. We're also looking at the use of teriparatide in conjunction with dental implant therapy. There are situations where patients need to augment their bone to be able to have an implant. We think this could be a promising avenue for that."
Side-effects
The other study, reported in a letter in the Journal, involved just one patient, an 88-year-old women whose jaw began to erode after a tooth was removed, a condition known as osteonecrosis. Conventional treatment did not help. The pain, which she had been experiencing for a year, persisted.
Doctors said the problem may have been her 10-year use of alendronate, commonly known as the Merck osteoporosis drug Fosamax, following a hip fracture. While Forteo spurs the growth of new bone, Fosamax slows the normal absorption of exiting bone.
"It's an uncommon but awful adverse event" with Fosamax, coauthor Dr Ego Seeman of the University of Melbourne in Australia said in a telephone interview.
Pain disappeared after 8 weeks
After eight weeks of Forteo injections, the woman's pain disappeared and CT scans showed that bone cells had rebuilt that portion of the jaw.
"It was complete repair and she was suffering horribly," Seeman said.
Osteonecrosis often comes from radiation therapy for head and neck cancer. Periodontal disease, cancer, chemotherapy, glucocorticoid therapy, or trauma can also cause it.
Recently, however, high-dose intravenous bisphosphonates have been identified as a risk factor for osteonecrosis of the jaw among oncology patients.
Seeman said Forteo might be a candidate for counteracting the problem. But Grey cautioned that such cases are so rare, it may be difficult to do a proper test to prove the treatment is effective.
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