Transient osteoporosis of the navicular bone in a runner

Excerpt

The authors are correct in their assumption that biphosphonates, in this case alendronate, tend to remain in the bone over extended periods of time—the half-life is believed to average about 10 years (product information). Therefore, a washout of the biphosphonates can be expected over years. In young women, a theoretical risk of side-effects remains in the case of pregnancy due to transplacenteal passage of the biphospophonates into the embryo. Interestingly, the liberation of alendronate is so limited that even during therapy, serum levels are almost undetectable. The study by Patlas et al. describes dosages of 0.1 mg/kg alendronate s.c. given to pregnant rats. These dosages are much higher than any seen in clinical treatment. Nevertheless, the authors are correct in suggesting that biphosphonates should only be administered in younger women when contraception is ensured. There are presently no data in the literature suggesting that embryopathies may be caused by secondary release of biphosphonates from the bone of expectant mothers following such treatment. …