Long-Term Bisphosphonates Beneficial, but Stopping Is Safe.

December 26, 2006

SAN FRANCISCO ? Postmenopausal women can stop taking Fosamax (alendronate) after five years without dramatic losses in bone density or an increased risk of fracture, according to researchers here.

SAN FRANCISCO, Dec. 26 -- Postmenopausal women can stop taking Fosamax (alendronate) after five years without dramatic losses in bone density or an increased risk of x-ray-detected fracture, according to researchers here.

But continuing to take the drug is safe and maintains most of the gains in bone density obtained in the first five years of therapy, said Dennis Black, Ph.D., of the University of California San Francisco.

Bone density drops in women who stop taking the drug but still remains at or above the level seen when they started, Dr. Black and colleagues reported in the Dec. 27 issue of the Journal of the American Medical Association.

The finding comes from a prospective blinded trial, in which 1,099 of the women who had been taking Fosamax during the earlier Fracture Intervention Trial were randomized to one of two doses of Fosamax (5 mg or 10 mg/day) or to placebo for another five years.

The risks of long-term therapy with bisphosphonates such as Fosamax had been unclear, especially because there have been cases of damage to the jawbones associated with the drugs, the researchers noted.

And it has also been unclear when - or if - women could safely stop taking the medications, they said.

The so-called Fracture Intervention Trial Longterm Extension (FLEX) lays those fears to rest and provides "important data that should enable clinicians to discuss the benefit side of the equation as well," commented Cathleen Coln-Emeric, M.D., of Duke in Durham, N.C.

"Armed with FLEX data, physicians may be able to begin telling women when they have had enough of a good thing," Dr. Coln-Emeric said in an accompanying editorial.

The FLEX study, compared with continuing Fosamax, found that:

  • Switching to placebo for five years resulted in an average 2.4% decline in bone mineral density at the total hip and a 3.7% decline in the spine.
  • Both differences were statistically significant at P