Older people who take antiepileptic drugs may be at higher risk of bone fractures, in part because the drugs can affect balance. But the drugs may also cause fractures more directly, by interfering with the body's attempts to deposit new bone. Researchers looked at women in Maryland, Minnesota, Oregon, and Pennsylvania to see how antiepileptic drugs affected them.

What the researchers wanted to know: Do older women on antiepileptic drugs lose bone faster than women who aren't on the drugs?

What they did: Nearly 10,000 women, most in their 70s or older, joined a study of osteoporosis between 1986 and 1988. Women had six examinations between then and 1997-1998 (4,815 women made it to the sixth round of visits). Researchers monitored bone density at the hip and the heel and also kept track of which medications women were on by asking the women to bring all their pill bottles and other medications to some of the appointments. Of the thousands of women, only 61 used antiepileptic drugs at some time. All of the women lived in the community, as opposed to being in an institution such as a nursing home.

What they found: Women on antiepileptic drugs lost bone faster from both their hips and their heels. This held true after adjusting for age, health, smoking, and other factors.

What the study means to you: Women taking antiepileptics should be tested for osteoporosis and may need to take calcium and vitamin D supplements, the authors write.

Caveats: The women in this study were quite elderly and white (black women were excluded because they rarely have hip fractures). Only a few women were taking antiepileptic drugs—not enough to distinguish between the different types of drugs.

Find out more: A long, fairly technical article from emedicine.com, describing the many different types of antiepileptics and how they work

Read the article: Ensrud, K.E., et al. "Antiepileptic Drug Use Increases Rates of Bone Loss in Older Women." Neurology. June 8, 2004, Vol. 62, No. 11, pp. 2051-2057.

Abstract online: http://www.neurology.org/