Bone Mineral Density With Lamotrigine Monotherapy for Epilepsy

Bone mass, largely accumulated during childhood and adolescence, may be reduced in patients with epilepsy as a result of epilepsy or of antiepileptic medications. Enzyme-inducing medications increase bone-turnover markers, although the effects of newer medications on bone accrual are not well-defined. Total z-score bone mineral density was measured in 13 children, treated with lamotrigine monotherapy, who had never been exposed to other medications, and compared with 36 control subjects and 40 patients exposed to polytherapy. All patients were normally ambulatory and had similar physical activity and calcium intake. The z-scores of bone mineral density for lamotrigine and control subjects were similar (0.52 ± 0.76 versus 0.49 ± 0.7) and higher than those receiving polytherapy for 1-5 years (0.14 ± 0.8, P = 0.12) and ≥6 years (-0.27 ± 01.15, P < 0.003). Increasing duration of epilepsy was associated with lower bone density for 1-5 years of polytherapy (Spearman's correlation coefficient r = +0.006, P = 0.74) and ≥6 years of polytherapy (Spearman's correlation coefficient r = +0.12, P = 0.13), but not for lamotrigine. These data suggest that lamotrigine may not interfere with bone accrual.