Impact of antiepileptic drugs on bone health: Need for monitoring, treatment, and prevention strategies

Epilepsy is the most common neurological disorder affecting approximately 50 million people worldwide. In India, overall prevalence of epilepsy is reported to be 5.59/1000 population. Antiepileptic drugs (AEDs) constitute the main-stay of treatment with a large number of AEDs available in the market. High incidence of adverse effects is a major limitation with AEDs. One of the major concerns is significant metabolic effects on the bone. However, little attention has been paid to this issue because most of the bone effects remain subclinical for a long time and may take years to manifest clinically. The main effects include hypocalcemia, hypophosphatemia, reduced serum levels of Vitamin D, increase in parathormone (PTH) levels, and alterations in bone turnover markers. The CYP450 enzyme-inducing AEDs such as phenytoin, phenobarbital, carbamazepine, and primidone are the most common AEDs associated with bone disorders while the data regarding the effect of valproate and newer AEDs such as lamotrigine, gabapentin, vigabatrin, levetiracetam, and topiramate on bone metabolism and bone density are scanty and controversial. Deficiency of Vitamin D is commonly described as a cause for the bone loss in epileptic patients while others being decreased absorption of calcium, increased PTH levels, and inhibition of calcitonin secretion, etc. However, there are no formal practical guidelines for the management of bone disease among those taking AEDs. Evidence-based strategies regarding monitoring, prevention, and treatment of bone diseases in patients on AED therapy are needed.