9704 Elderly Caucasian women were assessed for bone loss over 5 years in a multi-site population based study. Classified as either continuous user of anti-epileptic drugs (AED), partial users of AED or non-users of AED, these women's calcaneal and hip bone mineral density were measured in a series of up to 6 follow-up clinic examinations. The average decline in hip BMD was found to be -0.70% for non-users, -0.87% for partial users, and -1.16% for continuous users (p=0.015). BMD decreased disproportionately in the subregions of the hip and the calcaneus for continuous users. Overall, there was a 29% increase in the risk of hip fracture for continuous users, and the author notes that their findings "indicate that older women taking AED should be targeted for osteoporosis screening, including assessment of clinical risk factors for fracture, counseling regarding calcium intake and vitamin D supplementation, and consideration of bone density testing and laboratory evaluation for evidence of vitamin D deficiency."

Ensrud KE, Walczak TS, Blackwell T, Ensrud ER, Bowman PJ, Stone KL. Antiepileptic drug use increases rates of bone loss in older women: a prospective study. Neurology. 2004;62(11):2051-7.

http://www.neurology.org/cgi/content/abstract/62/11/2051