New FDA Labeling Suggests Stopping bisphosphonates after 3 to 5 years in low risk patients
Osteoporosis is a disease associated with a
reduction in bone mass and an increase in skeletal fragility.
It affects 10 million Americans; another 34 million are considered at risk.1
Bisphosphonates have been shown to be
effective in reducing the risk of osteoporotic fragility fractures,
and are widely prescribed for that purpose. During the
period from 2005 to 2009, 150 million prescriptions were dispensed in the United States outpatient
setting for three popular oral bisphosphonates: alendronate (Fosamax®), risedronate (Actonel®) and ibandronate (Boniva®) in the US.
Of these 150 million prescriptions, 5.1 million patients over the age of 55 received a
prescription for bisphosphonates in 2008.2
The long-term safety and efficacy of bisphosphonate therapy for
osteoporosis was evaluated by the FDA Advisory Committee for Reproductive Health Drugs and the Drug
Safety and Risk Management committee. Rare but serious
adverse events associated with long-term bisphosphonate use have been identified in post-marketing
surveillance reports. Cases have included atypical femur fractures, osteonecrosis of the jaw, and
esophageal cancer. The Committees jointly recommended that bisphosphonate labeling be
It is worth noting that bisphosphonates significantly accumulate in
skeletal binding sites because the receptors are essentially unsaturable. A reservoir is formed and drug is continuously released for
months to years, even after the drug is discontinued. This makes it possible for clinicians to
consider a ‘drug holiday’ for patients on bisphosphonate therapy after a certain period
In September of 2011, the FDA held a hearing
to review the long term safety and efficacy of bisphosphonates.
Consequently, they recommended that clinicians reevaluate the need for continued
bisphosphonate therapy beyond 3-5 years. They also stated that in patients at high risk, a drug
holiday may not be advisable.3 Currently, all bisphosphonates approved by
the FDA for the treatment of osteoporosis contain the following “Important Limitation of
Use” statement: “The optimal duration of use has
not been determined. All patients on bisphosphonate therapy
should have the need for continued therapy re-evaluated on a periodic basis.” FDA scientist Theresa Kehoe, MD, testified that the
agency’s own analysis concluded that there was no clear benefit or evidence of harm in women
who continued bisphosphonate therapy after five years, nor was there a “clear and
consistent” reduction in fracture risk.4
The committee recommended that the decision
to continue treatment with bisphosphonates should be based on individual assessment of risks and
benefits and patient preference. They indicated that
patients that are at low risk for fractures, meaning those that are younger and without a history
of fracture and a bone mineral density (BMD) near normal range, may be good candidates for
bisphosphonate therapy lasting for 3-5 years. On the other
hand, patients at increased risk of fractures, such as older patients with a history of
fractures, or bone mineral density in the osteoporotic
range, may benefit from continued bisphosphonate therapy.2
A double-blind, randomized, placebo-controlled trial called the
Fracture Intervention Trial (FIT) was conducted to study the effects of alendronate treatment on
fracture risk among 6459 postmenopausal women with low BMD.
FIT enrolled 3236 women on alendronate who were followed for an average of 3.8 years. The
investigators sought to determine if additional therapy with alendronate beyond this period would
result in preservation or further gains in BMD following alendronate discontinuation.
Subsequently, they conducted a follow-up,
double-blind, placebo-controlled extension trial to FIT, [FIT long-term extension (FLEX)] in which
1099 (39%) women from the FIT trial who had used alendronate for an average of 5 years were
re-randomized. To be eligible for the FLEX study, women had
to have been on alendronate for at least 3 years. Women were
randomly assigned to alendronate 10 mg/day (30%) (n=333), alendronate 5 mg/day (30%) (n=329) or
placebo (40%) (n=437) for a duration of 5 years.
Randomization was stratified by fracture risk; women with at least one radiographic
morphometric vertebral deformity identified by the end of FIT and/or who experienced a clinical
fracture during FIT were assigned to the high-risk stratum.
All participants were strongly encouraged to take a daily supplement containing calcium (500
mg) and vitamin D (250 IU). The percentage of participants
receiving the supplement was 97.5%.5
BMD of the total hip and its sub-regions,
together with the posterior-anterior lumbar spine, and the total body was measured at the FLEX
baseline using DXA and then repeated at 36 months using the same densitometers. At FLEX baseline, the average age was 73 years and 97% of
participants identified themselves as white. The average
duration of alendronate treatment was 5 years. The mean BMD
at the total hip corresponded to a T score of -1.9, mean BMD at the femoral neck corresponded to a
T score of -2.2, and mean BMD at the lumbar spine corresponding to a T score of -1.3. Thirty-eight percent of participants were assigned to the high
fracture risk stratum.5
The study showed lumbar spine BMD increased
in the alendronate group compared to the placebo group (5.26% vs. 1.52%), a mean difference of
3.74% (95% CI, 3.03%-4.45%; P<0.001). Similarly, in terms
of total body and forearm BMD, there was a statistically significant mean difference between the
alendronate (1.28%) and placebo group (2.01%) with (P<0.001 for both). In regards to nonvertebral fractures, no significant difference
was found between the pooled alendronate group and the placebo group. The percentage of fractures
was 19% with placebo vs 18.9% with alendronate. Although there was a statistically significantly
lower risk of clinical vertebral fractures in the alendronate group (5.3% with placebo vs 2.4% with
alendronate; RR, 0.45; 95% CI, 0.24-0.85), post hoc subgroup fracture analysis did not indicate any
significant trends with lower BMD or prevalent vertebral fractures at FLEX baseline for either
nonvertebral or clinical vertebral fractures. However, both
nonvertebral and clinical fractures were increased with lower baseline BMD or prevalent
fractures. The RR reduction in those who continued to take
alendronate was 55% and the absolute risk reduction was 2.9%.
It is clinically significant to note that women with a history of vertebral fractures or
very low BMD are at much higher risk of future vertebral fractures and have a higher absolute
benefit for prevention of vertebral fractures. The authors of the study report that gains in BMD
appeared to be better maintained after discontinuation of drugs in the bisphosphonate class,
including alendronate, risedronate, pamidronate and eidronate than with seen in patients treated
with estrogen, raloxifene or intermittent parathyroid hormones.6
Some of the limitations of this study include 1) limited power to
detect modest differences in fracture rates, as reflected in wide CIs for fracture outcomes, 2)
many FLEX participants were not diagnosed as having osteoporosis, either because they entered the
FIT trial without osteoporosis or because they experienced gains in BMD during FIT trial; thus
further reducing the power to detect a difference between groups, if one exists, 3) dose and
duration was not consistent throughout the trial, 4) the average age of the participants at
baseline was 73 years, causing the results to be non-generalizable to the general population (i.e.
younger women, men or the very elderly).
During the trial, there were no reports of
osteonecrosis of the jaw. There were no significant
between-group differences in upper gastrointestinal tract or serious upper gastrointestinal adverse
The authors concluded that continuation of
alendronate therapy for 10 years maintained both bone mass and reduced bone remodeling compared
with discontinuation after 5 years. With that being said,
even those who discontinued therapy after 5 years saw their BMD remain at or above baseline values
and bone turnover was still somewhat reduced.
Discontinuation of alendronate after 5 years did not increase the risk of nonvertebral
fractures over the next 5 years. However, the risk of
clinically diagnosed vertebral fractures was significantly increased among those who discontinued
therapy. These results suggest that women at high risk of
clinical vertebral fractures, such as those with vertebral fractures or very low BMD, may benefit
by continuing bisphosphonate therapy beyond 5 years; and that discontinuation of alendronate after
5 years in women at low risk of fractures does not significantly increase fracture
The results of this study mirrors the
recommendations of the FDA that patients on bisphosphonate therapy should be reevaluated after 3-5
years of therapy. Appropriateness of continued therapy based
on an individual’s risks and benefits should be assessed during the reevaluation period. Patients at high risk of future vertebral fractures, such as
patients with existing vertebral fractures, or patients with low BMD may benefit from continued
Guo, J, Kehoe, T, Benson, G. Bisphosphonate for
Osteoporosis—Where do we go from here? N. Engl J Med
366; 22. May 31, 2012
2. Division of Reproductive and Urologic
Products, Office of New Drugs Division of Pharmacovigilance II, Office of Surveillance and
Epidemiology, Office of Surveillance and Epidemiology Center for Drug Evaluation and Research Food
and Drug Administration: Background Document for Meeting of
Advisory Committee for Reproductive Health Drugs and Drug Safety and Risk Management Advisory
Committee. September 9, 2011.
3. Diab, D, Watts, N. Bisphosphonates drug holidays:
who, when and how long. Ther Adv Musculoskel Dis.
(2013). (3): 107-111.
4. Rubin, R.
FDA panel: Osteoporosis drugs need better labels.
Time limits on the drugs are
suggested, but how much time is yet to be determined. WebMD.
http://www.webmd.com/osteoporosis/news/20110909/fda-panel-unclear-on-osteoporosis-drug-labels. Accessed 07/16/2013.
5. Ensrud, K, Connor-Barrett, E, Schwartz, A,
Santora, A, Bauer, D C, Suryawanshi, S, Feldstein, A, Haskell, W L, et. al. Randomized trial of effect of alendronate continuation versus
discontinuation in women with low BMD: Results from the
fracture intervention trial long-term extension. Journal of
Bone and Mineral Research. Vol 19 (8), 2004: pp.
6. Black, D, Schwart, AV, Ensrud, KE, Cauley,
JA, Levis, S, Quandt, SA, Satterfiled, S, Wallace, RB, et. al.
Effects of continuing or stopping alendronate after 5 years of treatment: the fracture
intervention trial long-term extension (FLEX): a randomized trial.
JAMA, 12/27/2006. Vol 296(24): pp 2927-2936.