CHAPEL HILL - Studies of a drug known as Pamidronate indicate that the drug is highly effective in partially reversing the bone weakening known as osteoporosis due to drugs taken after various transplants, including lung transplants in cystic fibrosis patients.
The studies, described at the 12th Annual North American Cystic Fibrosis Conference in Montreal that ended Sunday (Oct. 18), found that patients treated with Pamidronate experienced about a 10 percent reversal of bone loss caused by immuno-suppressant drugs.
Drs. Robert M. Aris, assistant professor of medicine; David Ontjes, professor of medicine; and Gayle E. Lester, research associate professor of orthopaedics, all at the University of North Carolina at Chapel Hill School of Medicine, conducted the research with help from 35 cystic fibrosis patients. All patients had undergone lung transplants because of failing health.
"Several clinical trials, conducted in Europe and the United States, have explored ways to stop or reverse post-transplant osteoporosis but without much success," Aris said. "We think this is the first evidence not only that you can treat osteoporosis after lung transplantation for cystic fibrosis, but also it's the first evidence of a good drug response to osteoporosis after transplant."
Doctors are required to give patients steroids and immuno-suppressants such as cyclosporin to prevent transplanted tissue from being rejected.
"Although these drugs prevent rejection, unfortunately they weaken bones," Aris said. "They impact bones in a half-dozen or more ways such as by blocking calcium absorption in the gut, by promoting bone resorption, or breakdown, and by diminishing new bone formation. Higher fracture rates result after transplantation due in part to these immuno-suppressants."
Twenty-two of 35 lung transplant patients have completed the two-year Pamidronate treatment study at UNC-CH, including one who is an aerobics instructor. Most have markedly increased their activity levels because of improved lung function.
Overall, patients showed a 9 percent increase in their femur (hip) mineral densities and an 11 percent increase in spine mineral densities when compared with control subjects who received no Pamidronate.
Some 200 lung transplants take place in the world each year because of cystic fibrosis, Aris estimated, besides the 10,000 to 20,000 other kinds of organ transplants.
"If you consider all the transplants that take place here and in other countries, that's a very large number of patients who could benefit from this treatment if further studies confirm its effectiveness," he said.
UNC-CH researchers focused on cystic fibrosis lung transplant patients because they had severe osteoporosis, needed quick attention and had similar characteristics that would make the study more reliable, Aris said.
Novartis Pharmaceutical Corp. produces Pamidronate, which is administered intravenously. An oral drug known as Alendronate came on the market less than two years ago for people with osteoporosis from old age. That oral version is now being studied for transplant patients.
Eventually, the treatment may also allow some patients who now are disqualified from transplants because of pre-existing osteoporosis to undergo transplants, the physician said.
The Cystic Fibrosis Foundation funded the UNC-CH research with help from the National Institutes of Health.
By David Williamson
UNC-CH News Services
Note: Aris can be reached at (919) 966-2531.
Contact: David Williamson, 962-8596.