ABSTRACT:
Epilepsy is one of the most common neurological disorders. India is home to about 10 million people with epilepsy (prevalence of about 1%). Usage of anti epileptic drugs (AEDs) for 15 years is not uncommon, despite the fact that long-term AED therapy is a known risk factor for bone loss and is associated with abnormalities in calcium metabolism which include hypocalcemia, elevated levels of serum alkaline phosphatase, reduced serum levels of biologically active vitamin D metabolites, radiological evidence of rickets and histological evidence of osteomalacia. The present study was conducted to know the association of long term AED therapy and change in bone biochemical markers. This case-control study was conducted in June 2010 at a tertiary care hospital in South India. 80 patients and 20 controls, aged 20 to 40 years were enrolled for the study. All patients who were using AEDs for at least one year were included in the study. The following seven markers were measured to determine the risk of fractures namely serum calcium, serum phosphorous and 25(OH) D levels, bone formation markers - BSAP(Bone specific alkaline phosphatase) and osteocalcin, bone resorption markers - C-telopeptide and urinary hydroxyproline. Markers of both bone formation and bone resorption were significantly altered in cases when compared with controls. When the duration of exposure with the biochemical markers and the correlation was strongly significant. Linear regression analysis has revealed that there is 0.269mg/dl and 1.82ng/ml reduction in serum calcium and 25(OH)D level respectively every year in patients on enzyme inducing AEDs continuously. All other bone formation markers were decreased and bone resorption markers increased which was moderately significant. The present study documents that long treatment antiepileptic drugs cause change in bone biochemical markers, indicating altered bone function leading to increased risk of osteoporosis and fracture. Clinicians should monitor treatment with antiepileptic drugs either with biochemical markers or directly with bone mineral density.