Effects of the antiepileptics phenytoin and zonisamide on dentin formation and bone mineral density of the mandible in growing rats

A retrospective comparative fractal and radiomorphometric analysis of the effect of 3 generations of anti-epileptic drugs on the mandible

OBJECTIVE

The present study investigated the possible impacts of anti-epileptic drugs (AEDs) on trabecular and cortical bone in the mandible.

STUDY DESIGN

Fractal dimension (FD) and the radiomorphometric parameters of mandibular cortical width (MCW), panoramic mandibular index (PMI), and mandibular cortical index (MCI) were assessed on 497 dental panoramic radiographs (DPRs) of patients in the case group and controls. AEDs were compared according to 3 generations, duration of use, and patient age and sex.

RESULTS

FD of the angle and body of the mandible and MCW were significantly lower in the case group than in the control group (P < .001). FD values in the ramus and angle were lower in first-generation and third-generation AEDs than in second-generation drugs (P ≤ .011). FD in the mandibular body was lower in first-generation and second-generation AED users than in third-generation drugs (P = .017). Drug use for at least 1 year resulted in significantly lower values for all FDs and MCW values and more class 3 MCI assessments than short-duration use, but PMI was higher with more than 1 year of AED use (P ≤ .020). Age and sex had no significant effects.

CONCLUSIONS

AEDs caused significant changes in bone compared with controls in some FD values, MCW, and MCI. The effect of drug generation is pronounced in trabecular bone. Anti-epileptic drug use for more than 1 year had a greater effect than short-term use.

Effects of zonisamide monotherapy on bone health in drug-naive epileptic patients

OBJECTIVE

Alteration of bone strength is an adverse effect of antiepileptic drug treatment. We investigated the effects of zonisamide (ZNS) monotherapy on bone mineral density (BMD) and biomarkers of bone metabolism after 13 months of treatment in drug-naive epileptic patients.

METHODS

Fifty-nine patients with new onset drug-naive epilepsy were enrolled (29 women, 30 men; mean age = 31.5 ± 11.5 years). The BMD and T scores were measured at the lumbar spine and femoral neck by using dual-energy X-ray absorptiometry. Biomarkers specific for bone metabolism (bone-specific alkaline phosphatase, parathyroid hormone, osteocalcin, insulinlike growth factor-1, C-telopeptide, and vitamin D3 levels) were measured before and after long-term ZNS monotherapy. Analysis of covariance (ANCOVA) was used to estimate BMD and biomarkers of bone metabolism before and after ZNS therapy. Age, sex, treatment duration, and ZNS dosage were included as covariates for adjustment in the ANCOVA model. Furthermore, subgroup analyses were performed for each sex, and the effect size was calculated.

RESULTS

After 13 months of ZNS treatment, the BMD and T scores at the lumbar spine (L1-L4 level) and femoral neck were not significantly different. Moreover, the biochemical markers showed no significant differences after ZNS monotherapy. Women showed significantly decreased baseline BMD at the femoral neck compared to men (P = .026), although the mean age and body mass index were not significantly different between the sexes. No significant changes in BMD or biomarkers of bone metabolism were seen in either sex after 13 months of ZNS treatment.

SIGNIFICANCE

The results suggest that long-term ZNS monotherapy does not affect bone health in drug-naive patients with epilepsy negatively.

Levetiracetam, Phenytoin, and Valproate Act Differently on Rat Bone Mass, Structure, and Metabolism

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 (50 mg/kg), VPA (300 mg/kg), or LEV (50 and 150 mg/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.

Drug-induced gingival enlargement - Part II. Antiepileptic drugs: not only phenytoin is involved

INTRODUCTION: Gingival enlargement is the term now used to describe medication-related gingival overgrowth or gingival hyperplasia, a common reactionary phenomenon that occurs with the use of several types of therapeutic agents, including antiepileptic drugs. This disorder has been recognized since 1939, shortly after the introduction of phenytoin. METHODS: Review of literature concerning etiology, pathogenesis and management of antiepileptic drug induced gingival enlargement. CONCLUSIONS: It is important that neurologists become aware of the potential etiologic agents of antiepileptic drug induced gingival enlargement and its characteristic features in order to be able to prevent, diagnose and successfully manage it.