Levetiracetam, Phenytoin, and Valproate Act Differently on Rat Bone Mass, Structure, and Metabolism
Article first published online: 18 JUL 2007
Volume 48, Issue 10, pages 1850–1860, October 2007
How to Cite
Nissen-Meyer, L. S. H., Svalheim, S., Taubøll, E., Reppe, S., Lekva, T., Solberg, L. B., Melhus, G., Reinholt, F. P., Gjerstad, L. and Jemtland, R. (2007), Levetiracetam, Phenytoin, and Valproate Act Differently on Rat Bone Mass, Structure, and Metabolism. Epilepsia, 48: 1850–1860. doi: 10.1111/j.1528-1167.2007.01176.x
- Issue published online: 18 JUL 2007
- Article first published online: 18 JUL 2007
- Accepted April 19, 2007.
- Bone mineral content;
- Biomechanical strength
Summary: Purpose: Long-term treatment with antiepileptic drugs (AEDs) is associated with increased risk of fractures. Phenytoin (PHT) and valproate (VPA) have both been suggested to influence bone health, whereas levetiracetam (LEV) is scarcely studied. The present study compares the effect of these AEDs on bone mass, biomechanical strength, and bone turnover in rats.
Methods: Female rats received PHT (50mg/kg), VPA (300mg/kg), or LEV (50 and 150mg/kg) for 90 days. Dissected femurs were analyzed using dual energy x-ray absorptiometry (DXA), three-point cantilever bending, and histomorphological evaluation. Serum levels of biochemical bone turnover markers were monitored using immunoassay quantification.
Results: PHT and VPA reduced bone mineral density (BMD) and content (BMC) in one or more bone compartments, whereas LEV did not. VPA induced increased bone turnover, whereas modest changes were observed for PHT. Interestingly, low-dose LEV was associated with reduced biomechanical strength of the femoral neck (mainly trabecular bone). In addition, low-dose LEV treatment resulted in significantly reduced levels of serum osteocalcin, a marker of bone formation. Histomorphological analyses indicated increased retention of cartilage remnants at the growth plate metaphysis of rats treated with low-dose LEV vs. controls.
Conclusions: PHT, VPA, and LEV exert differential effects on bone mass and strength, suggesting different mechanisms of action. The weakening effect of low-dose LEV on the femoral neck, despite a constant BMD, suggests a primary effect on bone quality. These findings warrant further human studies of possible adverse effects of LEV on bone development and growth, particularly in children and adolescents.