A common scenario in the geriatric population is that the post-menopausal patient may be on a bisphosphonate for the treatment of osteoporosis. But when the patient is no longer mobile, wheelchair bound and the risk of fall is deemed to be low or moderate, the question arises as to whether she needs to continue her bisphosphonate therapy.
Bisphosphonates is a class of medications commonly prescribed for the prevention and treatment of osteoporosis. In Canada, oral bisphosphosnates including etidronate, risedronate and alendronate with risedronate and alendronate being most commonly prescribed for the treatment of osteoporosis due to their superior efficacy over etidronate. The dosing regimen ranges from once daily, once weekly to once monthly, depending on the patient’s preferences. One difficult aspect with this class of medications is around administration. The usual instruction is to swallow the medication whole on an empty stomach and the patient must sit upright for 30 minutes to ensure optimal absorption and to minimize gastric reflux which can lead gastric irritation and / or ulceration. This becomes challenging for frail elderly who may not be able to swallow tablets whole or to sit upright for 30 minutes.
The American Society for Bone and Mineral Research has provided some guidance on drug holiday with bisphosphonate therapy. For their detailed document, please click here. Below is the decision tree algorithm.
In essence, post-menopausal women who have been treated with oral bisphosphonates for ≥ 5 yrs (or IV bisphosphonates for ≥ 3 yrs), therapy should be reassessed. Factors to favour continued therapy include the following:
- Hip, spine, or multiple other osteoporotic fractures before or during therapy
- Hip BMD T-score ≤ 2.5
- High fracture risks
If all three conditions are absent, then drug holiday may be considered with reassessment to occur every 2-3 years. However, the task force report does not provide clear guidelines on how this reassessment should occur once the patient has discontinued bisphosphonate therapy. It hints that repeat BMD (bone mineral density) or BTM (bone turnover marker) measurements may guide future decision and recommends withholding bisphosphonate therapy if the BMD is stable but to restart if T-score is ≤ 2.5 or if other new / additional risk factors for fractures emerge.
Why Drug Holiday?
There are safety concerns with long term use of bisphosphonate therapy. It is now more apparent that there are concerns with rare but serious adverse effects such as osteonecrosis of the jaw as well as atypical femur fractures. There is some evidence suggesting that long term use of bisphosphonate therapy may put patients at higher risk of developing these two adverse effects. In addition, bisphosphonates may accumulate in bones and as such, there are residual benefits for up to 2-5 years after the medications have been stopped.
Here are my thoughts around drug holiday for bisphosphonate therapy:
- While the concept of drug holiday makes sense and certainly allows clinicians to make decision based on benefits and risks for each individual patient, it may not be easy to follow through in real practice. One reason is that we don’t have a good system to track patient’s duration of chronic therapy.
- Patients move around from pharmacies to pharmacies. So the most recent pharmacy record can provide details related to the patient’s most current medications but the pharmacy may not have all the history of what the patient has taken in the past or when they started their therapies.
- Patients may go from one institution to another. Sometimes during hospitalization for an acute event, bisphosphonate may be temporarily held and not restarted immediately, making it difficult to estimate the exact duration of therapy especially in patients with multiple admissions to hospitals or other institutions.
- Our current medication reconciliation process focuses on establishing the best possible medication history for the purpose of continuing the most appropriate medications at transfer but the process doesn’t always ask how long patient has been on their medications, rendering it difficult to assess if patient can go on drug holiday or not.
- Finally, there may be non-adherence factors at play. Patients may not always remember to take their medications or may believe they don’t require the medications. So just because the physician has started therapy 5 yrs ago, cumulative non-compliance days may lead to a much shorter duration.
Hence, we simply don’t have a good system to establish duration of therapy for our patients, other than relying on the clinician’s documentation of when they have started therapy or the patients’ recall which is not always reliable.
I also think it may not be realistic to reassess therapy based on BMD or BTM measurements. Often osteoporosis therapy may be discontinued due to immobility so it would be almost impossible to request a BMD done for a frail elderly who can barely move his or her leg up, let alone get on a BMD scanner for proper measurement.
I don’t have all the answers or solutions to fix this problem but I think what may be helpful is to include the start date of bisphosphonate therapy in the prescription record so that this information will hopefully be transferred and carried through. But with our current dispensing practice and system, it would not be easy to assess for drug holiday because we don’t always have an accurate way to determine patient’s duration of therapy.
What do you think? Do you agree with drug holiday? Do you think it would be a challenge to establish duration of therapy with our current dispensing practice?
Thank you for reading my post.