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New research into epilepsy medication and bone density loss

8 June, 2004

Anti-epileptic drugs can increase the rate of bone loss in older women, according to a study published in the journal Neurology.

Women
over age 65 who were taking drugs for epilepsy were losing bone mass at
nearly twice the rate of women who were not taking epilepsy drugs.

The
study involved over 6,000 women at least 65 years old. The women's bone
density in the heel bone was measured at the beginning of the study and
again an average of 5½ years later. At that time, the women's bone
density in the hip bones was also measured. Then around 4,200 of the
women completed another hip bone density test an average of 4½ years
later.

Women
who were taking epilepsy drugs had 1.8 times the rate of bone loss in
the heel bone than women who were not taking epilepsy drugs, and a 1.7
times greater risk of loss at the hip. The results did not change when
researchers adjusted for other risk factors, such as age, oestrogen
use, poor health status, inactivity, smoking and lower calcium intake.

Study author Dr Kristine Ensrud commented:

'If
this rate of bone loss is not addressed, the risk of hip fracture for
these women will jump by 29 per cent over five years. Older women
taking epilepsy drugs should be screened for osteoporosis and counseled
about the importance of getting enough calcium and taking vitamin D
supplements.'

Ensrud
said the two types of bone were tested because some researchers have
hypothesised that epilepsy drugs affect only one type of bone, which is
prevalent in the hip bone, but makes up only a fraction of the heel
bone.

The
researchers monitored the women's use of epilepsy drugs by asking them
to bring all of their current medications to their study appointments.
Women who were taking epilepsy drugs at each appointment were
classified as "continuous" epilepsy drug users. Women who were taking
epilepsy drugs at some but not all of the appointments were called
"partial" users.

The
study found that the more frequently these medications were used, the
greater the risk of bone density loss. Women who were continuous users
had the highest average rate of bone loss. Women who were partial users
had higher rates of bone loss than did women who did not take epilepsy
drugs at any point during the study. For the heel bone, the average
rate of bone loss was 1.46 per cent of bone mass per year for
non-users, compared to 1.74 per cent per year for partial users and
2.35 per cent for continuous users. For the hip bone, the rates were
0.7 per cent for non-users, 0.87 per cent for partial users and 1.16
per cent for continuous users.