Health Spectator

In the wake of our report on links between atrial fibrillation and bisphosphonate drugs such as Fosamax and Reclast, Health Spectator performed a routine follow-up investigation of the health claims and side effects of this class of drugs. We discovered that, contrary to the majority of reports we had read when researching the initial story, other complications from treatment with bisphosphonates were already known.

Specifically, a condition known as osteonecrosis of the jaw (a condition in which the bone tissue of the jaw literally dies) had previously been linked to taking Fosamax. A check of the Merck website on May 6 showed no mention of this possible complication either under side effects or dosing information. Nevertheless, we found that no less prestigious a group than the New York Academy of Science is sponsoring a conference on bisphosphonates and osteonecrosis of the jaw (ONJ) later this month. In fact, that conference is partially funded by Merck & Co., Inc, Novartis, and Procter & Gamble Pharmaceuticals, the major manufacturers of bisphosphonates.

What’s more, it turns out that the bisphosphonates have been associated with cases of osteonecrosis of the jaw since 2003. That’s when reports surfaced of bisphosphonate-associated osteonecrosis of the jaw (BON) linked to use of Zometa (zolendronic acid) and Aredia (pamidronate). Novartis manufactures pamidronate, as well as zolendronic acid under the names Zometa and Reclast. Zometa is used to treat bone loss in cancer patients and others who are undergoing a more rapid form of bone disintegration than occurs in osteoporosis. Reclast has been approved by the FDA for Paget’s disease and is being considered for treating osteoporosis.

For the most part, early reports of BON were associated with dental work, especially dental work that directly affected the jaw, such as tooth extraction. But then it became apparent that some BON episodes were spontaneous and not the result of dental intervention. The odds of suffering from BON are much greater as a result of dental intervention, so patients who are about to undergo therapy with zolendronic acid (or any bisphosphonate, for that matter) are urged to take care of any essential dental work before beginning treatment.

At this point, the possible complications of treatment with bisphosphonates are unfamiliar to many medical professionals, hence the interest in symposia such as the NYAS educational conference on ONJ and bisphosphonates.

Fosamax from Merck and Reclast, a bone-fortifying drug from Novartis AG, have been linked to atrial fibrillation in studies of their use to treat post-menopausal women for osteoporosis. Reclast, which is administered in a once-yearly intravenous infusion, showed slightly greater risk of the potentially life-threatening side effect than Fosamax, which is a pill taken daily or weekly.

The findings, published separately in The New England Journal of Medicine, seem to have come as a surprise to medical workers. The bisphosphonates, the class of drugs to which Fosamax and Reclast belong, had previously been considered completely safe.

Dr. Steven Cummings of the California Pacific Medical Center Research Institute reviewed Merck trials of Fosamax from 1997 and found a 50 percent increased risk of the cardiac arrhythmia. Specifically, of 6,459 women in the 1997 study, about half took Fosamax, and 47 developed atrial fibrillation, compared to just 31 among the women not taking the daily medication. Dr. Cummings reported those findings in a letter to the NEJM.

Atrial fibrillation can cause blood clots and stroke, among other complications.

Meanwhile, other researchers looked at 7,736 post-menopausal women with osteoporosis who were treated with Reclast. Novartis hopes to get FDA approval to sell Reclast for treating osteoporosis, having recently received approval for selling it to treat Paget’s disease. Reclast is the Novartis brand name for zoledronic acid.

The good news: tests showed that Reclast works at least as well as other bishosphonate drugs for treating osteoporosis. The bad news: 50 women among those who took Reclast versus 20 among those who did not, developed the arrhythmia. That’s a better than fifty percent increased chance of developing atrial fibrillation while taking Reclast.

Currently, about 1.8 million American women are taking Fosamax, which is Merck’s brand name for alendronate.

According to the American Heart Association, the likelihood of developing atrial fibrillation increases with age and three to five percent of people over 65 suffer from the disorder.