Duration of Alendronate (Fosamax) Therapy for Osteoporosis
Patients with osteoporosis should take alendronate for 3-5 years, after which they should be considered for drug discontinuation if they are at low risk for fracture. 1
Treatment Duration Guidelines
The optimal duration of bisphosphonate therapy is a critical clinical consideration due to their unique pharmacological properties:
The FDA label for alendronate specifically states: "All patients on bisphosphonate therapy should have the need for continued therapy re-evaluated on a periodic basis. Patients at low-risk for fracture should be considered for drug discontinuation after 3 to 5 years of use." 1
The American College of Physicians recommends treating osteoporotic women with pharmacologic therapy for 5 years (weak recommendation; low-quality evidence). 2
Rationale for Limited Treatment Duration
Bisphosphonates have unique pharmacological properties that support limited treatment duration:
Bisphosphonates accumulate in bone and create a reservoir that continues to release from bone for months or years after treatment is stopped. 3
Studies with alendronate suggest that if treatment is stopped after 3-5 years, there is persisting anti-fracture efficacy for at least 1-2 years. 3
The Fracture Intervention Trial Long-term Extension (FLEX) demonstrated that women who discontinued alendronate after 5 years showed only moderate decline in BMD and no higher risk of nonvertebral fractures compared with those who continued alendronate for 10 years. 4
Risk Stratification for Treatment Duration Decisions
Treatment duration should be based on fracture risk assessment:
For patients at low risk for fracture: Consider drug discontinuation after 3-5 years of use. 1
For patients at high risk for clinical vertebral fractures: Consider continuing beyond 5 years, as the FLEX trial showed a significantly lower risk of clinically recognized vertebral fractures (2.4% vs 5.3%) in those continuing alendronate beyond 5 years. 4
Monitoring After Discontinuation
After discontinuing alendronate:
Patients should have their risk for fracture re-evaluated periodically. 1
The American College of Physicians recommends against bone density monitoring during the 5-year pharmacologic treatment period for osteoporosis in women (weak recommendation; low-quality evidence). 2
After discontinuation, fracture risk reassessment should include clinical fracture risk history, new symptomatic fractures, FRAX, BMD, and/or spine imaging. 2
Potential Concerns with Long-Term Use
Long-term bisphosphonate use has been associated with rare but serious adverse events:
Uncommon side effects that have emerged with wide clinical use include osteonecrosis of the jaw, musculoskeletal complaints, and atypical fractures. 3
The risk of these events is small, and a clear cause-and-effect relationship has not been established, but they warrant consideration when deciding on treatment duration. 3
Key Takeaways
Alendronate therapy for osteoporosis should typically be limited to 3-5 years for most patients.
After this period, fracture risk should be reassessed to determine if continued therapy is warranted.
Patients at high risk for clinical vertebral fractures may benefit from continuing therapy beyond 5 years.
The residual effect of bisphosphonates after discontinuation provides ongoing fracture protection for 1-2 years.
Regular reassessment of fracture risk is essential after discontinuation to determine if therapy should be restarted.