Are there any issues with long-term use of alendronate (a bisphosphonate)?

Long-Term Alendronate Use: Rare but Serious Risks After 5 Years

After 5 years of alendronate therapy, patients at low-to-moderate fracture risk should strongly consider a drug holiday to reduce the risk of atypical femoral fractures (AFFs) and osteonecrosis of the jaw (ONJ), while those at high fracture risk should continue therapy or switch to alternative treatments 1, 2.

Key Safety Concerns with Prolonged Use

Atypical Femoral Fractures (AFFs)

The risk of AFFs increases substantially with duration of bisphosphonate use beyond 5 years 1:

• Risk progression: Approximately 3 per 100,000 person-years at 2 years, increasing to ~20 per 100,000 at 5 years, and ~50 per 100,000 with >8 years of use 1
• Risk reduction with discontinuation: AFF risk decreases by approximately 80% within 3 years after stopping bisphosphonates 1
• Clinical presentation: Patients often report prodromal thigh or groin pain with weight-bearing activities before complete fracture occurs 1, 3, 4

While these fractures are rare, the risk increases dramatically with longer treatment duration. Multiple case reports document bilateral atypical femoral fractures after 10-15 years of unsupervised alendronate use 3, 4, 5, 6.

Osteonecrosis of the Jaw (ONJ)

• Baseline risk: 1 in 10,000 to 1 in 100,000 (0.001% to 0.01%) in osteoporosis patients 1
• Long-term risk: Increases to 21 in 10,000 (0.21%) after >4 years of oral bisphosphonate therapy 1
• Dental procedures: Tooth extraction carries a 0.5% risk of developing ONJ in bisphosphonate-exposed patients 1
• Prevention: Complete necessary dental work before starting bisphosphonates and maintain routine dental care 1, 7

Other Safety Considerations

• Upper GI irritation: Can be minimized with proper dosing technique (take with full glass of water, remain upright 30 minutes, empty stomach) 1, 7
• Renal function: Contraindicated if eGFR <35 mL/min for alendronate 1
• Hypocalcemia: Ensure adequate calcium (1200 mg daily) and vitamin D (800-1000 IU daily) supplementation 1, 7

Evidence-Based Treatment Duration Algorithm

For Patients at Low-to-Moderate Fracture Risk:

• Consider drug holiday after 5 years of oral alendronate or 3 years of IV zoledronic acid 1, 8
• During holiday, fracture efficacy is maintained for 3-5 years as BMD gains remain (though slowly lost) and bone turnover markers remain initially suppressed 1
• Re-evaluate fracture risk periodically during the holiday 2

For Patients at High or Very High Fracture Risk:

• Continue bisphosphonate therapy up to 10 years for oral formulations or 6 years for IV zoledronic acid 8
• Alternatively, switch to another osteoporosis therapy (denosumab, teriparatide, romosozumab) 1
• High-risk criteria include: femoral neck T-score ≤-2.5 at time of potential discontinuation, prevalent vertebral fractures, or age >75 years 1

Monitoring During Drug Holidays:

• Resume therapy if: patient experiences new fracture, shows significant BMD loss, or bone resorption markers rise to pretreatment levels 8
• Holiday duration varies by agent based on bone-binding affinity: longest after zoledronic acid, shortest after risedronate, intermediate after alendronate 8

Benefit-Risk Balance

The benefits of bisphosphonate therapy strongly outweigh AFF risks for up to 5 years in high-risk patients 1:

• Treating 1000 osteoporotic women for 3 years prevents approximately 100 fractures (including 11 hip fractures) while causing only 0.08-0.1 AFFs 1
• Hip fractures carry 300-400 per 100,000 person-years incidence—nearly 100-fold higher than AFF incidence 1

However, no comparable benefit-risk analyses exist for treatment beyond 5 years 1, making the case for drug holidays in appropriate patients particularly compelling.

Critical Clinical Pitfalls

1. Unsupervised long-term use: Multiple case reports document severe complications from >10-15 years of continuous alendronate without specialist monitoring or consideration of drug holidays 3, 4, 5

2. Inadequate calcium/vitamin D: Patients avoiding supplementation due to concerns about constipation or kidney stones may experience compromised bone health and increased fracture risk 3

3. Ignoring prodromal symptoms: Thigh or groin pain in long-term bisphosphonate users warrants immediate imaging evaluation, not dismissal as age-related complaints 1, 3

4. Failure to reassess: The FDA label explicitly states that "all patients on bisphosphonate therapy should have the need for continued therapy re-evaluated on a periodic basis" 2

The 2019 Endocrine Society guidelines 1, 2020 AACE guidelines 8, and 2023 ACP guidelines 9 all converge on the recommendation for treatment reassessment at 3-5 years, with drug holidays for lower-risk patients to mitigate rare but serious long-term complications.