From the FDA Drug Label
2.6 Treatment of Paget’s Disease of Bone The recommended dose is a 5 mg infusion. The infusion time must not be less than 15 minutes given over a constant infusion rate. Re-treatment of Paget? s Disease After a single treatment with zoledronic acid injection in Paget’s disease an extended remission period is observed. Specific re-treatment data are not available However, re-treatment with zoledronic acid injection may be considered in patients who have relapsed, based on increases in serum alkaline phosphatase, or in those patients who failed to achieve normalization of their serum alkaline phosphatase, or in those patients with symptoms, as dictated by medical practice.
The frequency of checking alkaline phosphatase in patients with Paget’s disease is not explicitly stated in the drug label. However, it is mentioned that re-treatment may be considered in patients who have relapsed, based on increases in serum alkaline phosphatase. This suggests that alkaline phosphatase levels should be monitored to determine the need for re-treatment 1.
- Key points:
- Monitor alkaline phosphatase levels to determine the need for re-treatment.
- The frequency of monitoring is not specified, but it should be done as dictated by medical practice.
From the Research
For patients with Paget's disease, alkaline phosphatase (ALP) levels should be monitored every 3-6 months initially after diagnosis or treatment, then annually once disease stability is established, as supported by the most recent study 2. After starting bisphosphonate therapy, such as zoledronic acid 5mg IV once, alendronate 40mg daily for 6 months, or risedronate 30mg daily for 2 months, check ALP at 3 months post-treatment, then at 6 months, and subsequently every 6-12 months to assess treatment response, as indicated by 3 and 4. Some key points to consider when monitoring ALP levels in patients with Paget's disease include:
- More frequent monitoring (every 3 months) is appropriate for patients with active, symptomatic disease or those with complications like fractures or nerve compression, as suggested by 5 and 6.
- ALP serves as the primary biomarker for Paget's disease activity because it reflects osteoblastic activity and correlates well with disease extent and severity, as noted in 2 and 6.
- A rising ALP level (25% or more above nadir) typically indicates disease relapse and may warrant retreatment, while normalized or stable ALP levels suggest adequate disease control, as indicated by 3 and 4.
- Patients with normal baseline ALP but active focal disease may require bone-specific ALP testing or additional imaging rather than standard ALP monitoring alone, as suggested by 5 and 6. It is essential to prioritize the patient's morbidity, mortality, and quality of life when determining the frequency of ALP monitoring, as the goal of treatment is to improve these outcomes, as supported by 2 and 6.