An osteoporosis drug with the potential to cut the risk of spine fractures by 70 percent and the chance of hip fractures by 41 percent, has been found to have an adverse side effect on some women.
Researchers say the drug Reclast which is produced by Novartis, which is given once a year, reduces the risk of broken bones for three years but it may spark an abnormal heart rhythm in some patients.
The study leader Dr. Dennis Black of the University of California San Francisco, says Reclast represents an excellent alternative for those who cannot or do not want to take oral drugs; however serious atrial fibrillation, an abnormal heart rhythm that can increase the risk of stroke, was found to be nearly three times more common among women taking Reclast.
Of 3,889 volunteers using the drug and 3,876 given placebo injections, one in 77 Reclast patients developed the problem.
Dr. Black says for the first time, women have the option of being treated once a year for osteoporosis, instead of having to remember to take a weekly pill.
Reclast represents an excellent alternative for those who cannot or do want to take oral drugs and is already approved in more than 50 countries to treat the abnormal bone growth of Paget's disease.
One injection of Reclast has been shown in studies to increase bone density for a year, whereas conventional oral drugs as a rule produce a 40 to 50 percent reduction in spine bone breakage.
Reclast is currently under review in the U.S. for osteoporosis; outside the United States it is called as Aclasta.
Reclast also produced other side-effects with 31.6 percent of recipients experiencing fever, joint and muscle pain, headache, or flu-like symptoms after their injections, compared to 6.2 percent who got placebo injections.
But the chance of having any of those symptoms dropped to 6.6 percent with the second yearly injection, and 2.8 percent with the third.
A once-a-year treatment for osteoporosis is preferred by doctors because patients do not always take other medication regularly.
A similar effect has been seen with Merck's equivalent Fosamax which is the same class of drug but is taken in an oral form.
Fosamax, is used by an estimated 1.8 million American women but a study by Dr. Steven Cummings of California Pacific Medical Center Research Institute has found a 50 percent higher risk of the serious heart rhythm in women who took the daily pill.
The study involving 6,459 women, half of whom took Fosamax while the other didn't, found there appeared to be 50 percent more risk of the serious heart rhythm in women taking the pill than among those who didn't take it; about half of the 6,459 women took Fosamax, and 47 developed atrial fibrillation, compared to just 31 cases among the other women.
Experts say this is a cause for concern and must be given serious consideration, while the researchers say it is unclear if the side-effects are a random event or the true effects of the drug or if the risk applies to other drugs in the class known as biphosphonates.
Osteoporosis affects millions of women worldwide, with more than 50 million women in the United States, Europe and Japan suffering from the ailment.
The two reports are published in the current issue of The New England Journal of Medicine.