How safe is bone health in patients on newer or enzyme inhibitor antiepileptic drugs?

The impact of antiseizure medication on bone heath: A systematic review of animal studies

BACKGROUND

Antiseizure medications (ASMs) are known to potentially impact bone health, but existing literature presents conflicting results regarding their specific effects on bone mineralization, metabolism, and quality.

OBJECTIVE

This systematic review aims to establish a consensus regarding the influence of ASMs on bone health based on existing preclinical studies.

METHODS

Following SYRCLE and PRISMA guidelines, we conducted a systematic search in PubMed, Science Direct, and Google Scholar to identify relevant studies. Ultimately, 21 articles were selected for inclusion in this review.

RESULTS

Among the chosen studies, approximately half involved Wistar rats as experimental subjects. Levetiracetam and sodium valproate were the most frequently investigated drugs, with a typical treatment duration of 10-12 weeks. These studies exhibited a low risk of bias in aspects like sequence generation, random housing, random outcome assessment, and reporting bias. However, blinding in performance, allocation concealment, and detection were often rated as having a high risk of bias. The collective findings suggest that prolonged ASM use leads to reduced bone mineral density, altered bone turnover marker levels (including hypovitaminosis D, hypocalcemia, and secondary hyperparathyroidism), deterioration of bone microarchitecture, and decreased mechanical strength.

CONCLUSION

The adverse effects on bone associated with ASMs are not limited to enzyme-inducing drugs, as newer generation ASMs may also contribute to these effects. Hypovitaminosis D alone may not be solely responsible for ASM-induced bone issues, suggesting the involvement of other mechanisms. Furthermore, substantial variations were observed in the results of different preclinical studies on individual ASMs, highlighting the need to standardize animal study methodologies to enhance reproducibility and reduce variation.

Bone mineral density and fractures in institutionalised children with epilepsy and intellectual disability

BACKGROUND

Long-term use of antiseizure drugs is associated with a low bone mineral density (BMD) and an increased fracture risk. The literature regarding institutionalised children on chronic antiseizure drugs is limited. Therefore, the aim of this cross-sectional study is to evaluate the prevalence of low BMD and the history of fractures in institutionalised children with epilepsy and intellectual disability (ID).

METHODS

A dual-energy X-ray absorptiometry of lumbar spine (L1-L4) and hip was performed in 24 children, residing in a long-stay care facility in the Netherlands. Additionally, serum concentrations of albumin, calcium and 25-hydroxyvitamin D were determined. Data on fractures were retrospectively extracted from the medical files.

RESULTS

Ages of the children (14 male and 10 female) ranged from 5 to 17 years with a mean age of 13.0 (±3.2). The criteria of the International Society for Clinical Densitometry (ISCD) were used for classification of bone mineral disorders. Eight (33.3%) children had a normal BMD (Z-score > - 2.0). Of the 16 children with a low BMD (Z-score ≤ - 2.0), three were diagnosed as osteoporotic, based on their fracture history. Ten children (41.7%) were reported to have at least one fracture in their medical history. Serum concentrations of albumin-corrected calcium (2.28-2.50 mmol/L) and (supplemented) vitamin D (16-137 nmol/L) were within the normal range.

CONCLUSIONS

This study demonstrated that 67% of institutionalised children with epilepsy and ID had low BMD and 42% had a history of at least one fracture, despite supplementation of calcium and vitamin D in accordance with the Dutch guidelines.

Prevalence and incidence of vertebral fractures: a 7-year follow-up study in institutionalized adults with refractory epilepsy and intellectual disability

OBJECTIVE

The main objective of this cohort study is to determine the prevalence and incidence of morphometric vertebral fractures (VFs) over 7 years follow-up, in institutionalized adults with refractory epilepsy and intellectual disability (ID).

METHODS

Dual-energy X-ray Absorptiometry (DXA) and Vertebral Fracture Assessment (VFA) were performed in 2009 and 2016. Vertebrae T4-L4 were assessed using quantitative morphometry. Severity of VFs was graded as 1 (mild; 20-25% reduction in height), 2 (moderate; 25-40% reduction) or 3 (severe; >40% reduction) according to the method described by Genant. Prevalent VFs were analyzed at baseline. VFs (grade 1, 2 or 3) present at follow-up, but not at baseline, were considered new VFs. Worsening VFs were defined as VFs with at least one grade deterioration at follow-up, compared to baseline (grade 1 to 2 or 3, or grade 2 to 3). Patients were treated with anti-osteoporosis treatment according to the Dutch guideline.

RESULTS

Baseline and follow-up DXA and VFA could be obtained in 141 patients (87 male) aged between 18-79 years old (mean 44.8 ± 15.7). At baseline, 56 patients had at least one prevalent VF. Patients with a prevalent VF were significantly older than patients without (49.2 ± 13.7 vs 41.9 ± 16.4, p < .01). After 7 years follow-up, 38 new VFs occurred in 27 patients and 15 patients had a worsening VF, leading to an overall cumulative incidence of 27.0%. VF incidence was significantly higher in patients with at least one prevalent VF at baseline (48.2% vs 12.9%, respectively, p < .01) compared to no VF.

SIGNIFICANCE

In adults with refractory epilepsy VFA is challenging, due to physical and behavioral aspects, resulting in a substantial proportion of unevaluable vertebrae and scans. Nevertheless, 40% of the patients had a VF at baseline and after 7 years follow-up, 27% had at least one new and/or worsening VF despite adequate anti-osteoporosis treatment.