Abstracts

Rationale: Anti-epileptic Drug (AED) use has been shown to be a risk factor for metabolic bone disorders. The pathophysiology of AED induced osteoporosis is unclear. The process may involve mechanisms other than hepatic microsomal enzyme induction. We investigated the differences in BMD between patients on enzyme inducing (EI) versus non enzyme inducing (NEI) AEDs. Methods: We screened a database of 169 subjects with epilepsy and Dual X-Ray Energy Absorptiometry (DEXA) results. We included only those aged 50 or younger (n=20) to minimize the impact of age-related osteoporosis. Patients were separated in to 2 groups depending on enzyme inducing versus non-enzyme inducing drug use. One way ANOVA was used to compare differences in spine and hip BMD between the two groups. Results: The mean age was 35.9(SD 9.4) years with male:female ratio of 9:11. Seven patients (35%) had normal DEXA, 11 (55%) had osteopenia and 2 (10%) had osteoporosis. To know whether the drugs differentially influenced BMD in both groups, we analyzed hip and spine BMD in both groups. The mean hip BMD and spine BMD was 0.963±0.260 g/m2 and 1.154±0.140 g/m2 respectively in the EI group vs 0.840±0.222 g/m2 and 1.089±0.468 g/m2 respectively in the NEI groups with no statistically significant differences between the groups.(P=0.37) Conclusions: Our results demonstrate that there is no correlation between the type of drug used (EI vs. NEI) and BMD. This result is complementary to our earlier finding of lack of correlation between Vitamin D levels and BMD. We conclude that AED-induced osteoporosis likely involves other pathophysiologic mechanisms in addition to Vitamin-D deficiency. A larger prospective trial is underway to confirm these preliminary observations.