Uncertainties about drug holidays

Tuesday, 29 November 2011 12:29

One of the great debates is how long is long enough for treatment. This debate is fueled by a number of things we just do not know yet. 

1) We don't know exactly how much of the benefit stays after a bisphosphonate has been stopped. Researchers believe there is continuing advantage from the drug for a few years.

2) We aren't sure exactly how long the drug benefit lasts in different kinds of bones – particularly the hip and the spine bones. Patients who were on a treatment for five years and off for five years did about as well as those staying on treatment for the entire ten years.

3) We aren't clear about when to restart an osteoporosis treatment after a drug holiday.

To help with these uncertainties, doctors are measuring bone metabolism with blood tests called bone turnover markers. As long as the results of the bone markers are low, it is logical that the drug is still having an effect in reducing fracture risk. The research on one bisphosphonate (alendronate) shows that the markers can stay low for 6-12 months after stopping treatment, but research into other osteoporosis drugs shows much shorter continued benefit after stopping. The carry-over effect depends on how long the drug remains in the bone and how much of it is released from bone back into the blood stream and eliminated from the body.