Effect of Antiepileptic Drugs on Bone Mineral Density and Bone Metabolism in Epileptic Patients

ABSTRACT

BACKGROUND: Bone mineral density (BMD) is influenced by genetic, hormonal, and environmental factors. Long-term antiepileptic drug (AED) use also causes osteopenia or osteoporosis that have been most extensively described in institutionalized patients. But, the mechanism of these abnormalities is unclear. The objective of this study is to determine the effect of AED on bone density and to explain the pathophysiologic mechanisms by analyzing bone related factors. METHODS: We prospectively examined BMD by dual-energy X-ray absorptiometry in 45 patients with epilepsy. We measured the serum calcium, phosphorus, protein, alkaline phosphatase (ALP), bone specific ALP, vitamin D and osteocalcin to analyze the factors that influence bone metabolism. RESULTS: BMD was significantly lower in the patient group than in the control group (p<0.05). 13% of patients had osteopenia and 3% of patients had osteoporosis. The level of bone specific ALP was higher in the patient group, but the level of vitamin D was not different, implying that BMD is decreased by the direct effect of antiepileptic drugs. There was a weak negative correlation and marginal significance between BMD and the duration of therapy in the patient group (r=-0.407, p<0.05). CONCLUSIONS: Long-term antiepileptic drug therapy in patients who have seizures causes significant bone loss in the lumbar spine even in the absence of vitamin D deficiency. In addition, the degree of bone mineral density was weakly related with the therapeutic duration of antiepileptic drugs. The regular evaluation of BMD in patients with long-term antiepileptic drugs might be helpful to prevent decreases in BMD.