Seizure drugs tied to bone loss in older men

NEW YORK (Reuters Health) - Use of certain seizure drugs called non-enzyme-inducing antiepileptic drugs or NEIAEDs (clonazepam, ethosuximide, gabapentin, and others) raises the risk of bone loss in older men, new research indicates.

In the journal Neurology, Dr. Kristine E. Ensrud, from the VA Medical Center, Minneapolis, Minnesota, and colleagues point out, "antiepileptic drug use may be associated with higher rates of bone loss because (the drugs) may have adverse effects on bone metabolism. On the other hand, antiepileptic drug use may be a marker of factors such as poor health...that are associated with greater rates of bone loss."

In 4,222 older men enrolled in the Osteoporosis Fractures in Men study, the researchers analyzed use of NEIAEDs and enzyme-inducing antiepileptic drugs or EIAEDs (carbamazepine, phenytoin, phenobarbital, and others). They also measured subjects' bone thickness at the hip when the study began and again 5 years later.

During follow-up, bone thickness fell to a greater extent in NEIAED users than in EIAED users or in men who didn't use seizure drugs at all.

"Our results suggest that NEIAED use is associated in a graded manner with rates of hip bone loss in older men with lower rates of loss among nonusers of antiepileptic drugs, intermediate rates of loss among intermittent users, and high rates of loss among continuous users," the authors write.

They added, "These findings are supported by prior studies reporting higher fracture rates among NEIAED users compared with nonusers of antiepileptic drugs or a similar fracture risk between patients taking NEIAEDs versus those taking EIAEDs."

SOURCE: Neurology, September 2, 2008.