Does a patient’s osteoporosis complicate sedation?

Dr. Mark Chunn, Fellow with DOCS Education, writes:

I have a 71-year-old female whom I have seen several times over two years ago when we removed a couple of teeth. Recently she presented with a minor problem that was addressed on an emergency basis (limited exam). I have recommended that she return for a complete exam and radiographs in order to formulate a treatment plan. In reviewing her medical history, I learned that she was placed on Alendronate one month ago by a nurse practitioner. She also takes Metformin and Pravastatin.

Due to the fact that she probably is not in good dental health and possibly will need additional extractions, is it prudent (and effective) for me to recommend discontinuation of the Alendronate until we can be assured that she will not need any extractions? I do not understand how long someone takes a bisphosphonate before the risks of post extraction necrosis become significant. Nor do I understand if it will benefit her to discontinue it after starting it 30 days ago. Her nurse practitioner said it would be fine if I choose to discontinue it for a while.

The nurse also asked my opinion on changing her to Forteo^® (a relatively new, injectable treatment for osteoporosis that apparently has a different mechanism of action via the parathyroid gland). She claims that its half-life is quite low and suggested that maybe it could be a better treatment in the future for patients who need to discontinue therapy for similar reasons.

My limited research indicates that Forteo^® may actually be a good treatment for persons who develop osteonecrosis following extractions. Not surprisingly, it comes with its own risks of bone cancer. I feel there is lots of opportunity to discuss several ideas here. Please give me your thoughts about how I should proceed.

Dr. Leslie Fang, Medical Director of DOCS Education Faculty, responds:

While the risk of osteonecrosis of the jaw is very pronounced in patients on intravenous bisphosphonates for cancer, the risk of ONJ on oral bisphosphonate is actually small, with the best estimate at less than 0.1%.

It is clear that there are a number of factors that should be considered in assessing risks:

1. Age of patient: the older the patient, the higher the risk
2. Presence of infection
3. Duration of bisphosphonate treatment: seldom reported in patients who are on bisphosphonates for less than 6 months. Most of the cases have been on therapy for more than 5 years
4. Diabetes mellitus
5. History of steroid use

This patient is elderly, has evidence of infection, has diabetes but has been on bisphosphonates for a short duration of time.

There is no data on "drug holiday" that is convincing since bisphosphonates will intercalate into bones

for decades, but it is now commonplace for clinicians to give patients Fosamax^® holidays after 5 years of therapy: whether this is a correct approach is being examined.

It would be difficult to believe that there will be significant push to Forteo^® on the basis of the following concerns over the risk of ONJ, which are small as previously indicated:

1. Cost
2. Usually reserved for patients who have failed oral bisphosphonates (and the insurance company often wants documentation of the same)
3. The risk of bone cancer

In this patient, because of the short duration of therapy with an oral bisphosphonate, her risk is finite. I do not believe that being off bisphosphonates for a short period of time is all that helpful, based on the physiology, but it might make you feel better.

In short, you should proceed per your normal protocol.

Another DOCS Education member has an additional question:

I'd be happy to be corrected here if I'm wrong, but I was of the impression that the half-life of these drugs typically isn't all that useful (at least for the traditional bisphosphonates such as alendronate). As it works by decoupling the osteoblast/osteoclast relationship, the medication ends up in the bone almost indefinitely. I haven't had the opportunity to look into Forteo^® in any real depth, but would this be different or similar?

Dr. Fang responds:

What you mentioned about half-life is correct for all of the bisphosphonates but NOT for Forteo^®.

Forteo^® is not a bisphosphonate but is a biologic recombinant Parathyroid hormone, or PTH. PTH is an important hormone in calcium metabolism. Given chronically, it will mobilize calcium from bone and cause depletion. However, when given intermittently, it stimulates osteoblasts (bone growth) more than osteoclasts (bone loss).

It has to be given daily as a subcutaneous injection (20 ug) and the annual cost of the medication is $6,700, more than 8-10x that of bisphosphonate.