Fosamax – Can You Stop After 5 Years?

Stopping aledronate (Fosamax) after 5 years of use may be a reasonable option for many women using this osteoporosis-fighting drug, according to a research study published this week in the Journal of the American Medical Association.

In this multicenter study, which was funded by Fosamax manufacturer, Merck, and designed jointly by both Merck and non-Merck investigators, women who had been using Fosamax for 5 years were randomly assigned to continue aledronate for another 5 years, to continue for 5 years at a lower dose, or to take a placebo for 5 years.

Not surprisingly, stopping aledronate after 5 years led to a decline in bone mineral density at both the hip and the spine, and bone turnover increased. The loss of bone, though significant, was small, so that bone densities five years later were still higher than they were when aledronate was first started.

Women who stopped aledronate after 5 years did not have an increase in the rate of new non-vertebral fractures.

However, there was a significantly higher risk of vertebral fractures in women who stopped aledronate.

The protection provided by continuing aledronate beyond 5 years was evident among women whose T scores (measured at the hip) were below -2.0 at baseline and in women who had a prior risk of fracture. For women whose baseline bone density was above -2.0, the risk for fracture was the same whether or not they stopped or continued aledronate.

It should be reassuring to Fosamax users to know that no excess in adverse events occurred in the 10 year Fosamax use group, and no cases of osteonecrosis of the jaw were reported in the over 1000 Fosamax users in this study. There were also few differences in outcomes when the 5mg and 10 mg Fosamax doses were compared.

Understanding the results

Bone is a living tissue, undergoing constant reformation via a delicate balance between the breakdown of old bone by osteoclasts and the formation of new bone by osteoblasts. If bone breakdown exceeds bone formation, bone loss results.

Fosamax is one of a class of drugs called bisphosphonates. These drugs bind to the bone to cause the aptosis (cell death) of osteoclasts. This shifts the balance of bone turnover in favor of new bone formation.

Bisphosphonates bind very tightly to bone and can remain there for up to ten years. During this time, they continue to increase bone density and prevent fractures. Although no adverse effect of prolonged use has been reported, concerns remain, particularly in light of recent reports about osteopnecrosis of the jaw in bisphosphonate users. Interest has been growing to find ways to limit bisphosphonate use to shorter periods of time. This study was done in order to determine if Fosamax use could be limited to 5 years and still be effective.

Bottom Line

If you have been taking aledronate for 5 years, and your hip T score is above -2.0, it appears that you can stop your aledronate for 5 years without increasing your fracture risk. Women with certain medical conditions or at increased risk for fracture may do best to stay with with their medciation, so talk to your doctor to see if this applies to you.

If your hip T score is less than -2.0, then stopping aledronate will not increase you chance of a hip fracture over the next 5 years, but your risk of spinal fracture will increase. This increased risk is small and should be weighed against the risks of continuing the drug. Talk to your doctor about your options. If you are at high risk for fracture, it is probably advisable to continue taking you medication. A a one to two year drug holiday might be a good compromise between stopping your medication altogether and staying on it continuously. You could also consider lowering the dose.

If you do stay on bisphonsphonates for 10 years or more, be reassured that to date, long term use has not been found to increase the risk for adverse events.

Do these results with aledronate apply to other bisphosphonates, in particular, risedronate or Actonel? We have no data, but Actonel has a similar mechanism of action and duration of action to Fosamax, so it may not be unreasonable to expect similar results. Again, talk to your doctor.

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Patient information about osteoporosis from the National Osteoporosis Foundation and from The Hospital for Special Surgery.

Physician’s Guide to the Prevention and Treatment of Osteoporosis. This great resource from the NOF is downloadable and free with registration.

Category: Second Opinions