Frequency of and risk factors for oxcarbazepine-induced severe and symptomatic hyponatremia

Purpose: Hyponatremia is one of the most common adverse effects in patients treated with oxcarbazepine (OXC). Most patients with OXC-induced hyponatremia are asymptomatic, so the presence of severe or symptomatic hyponatremia, which requires electrolyte correction or discontinuation of OXC therapy, has more important clinically implications. However, data for OXC-induced severe and symptomatic hyponatremia are limited.

Methods: We reviewed medical records of all patients with epilepsy who were treated with OXC at the Seoul National University Hospital. We analyzed serum sodium level results and attempted to identify correlations between various factors and the frequency of severe and symptomatic OXC-induced hyponatremia.

Results: Data from a total 1009 patient were examined. The frequency of severe and symptomatic hyponatremia was 11.1% and 6.8%, respectively. Multivariate analysis revealed that age (P=0.014, OR 1.014), antiepileptic drug (AED) polytherapy (P=0.040, OR 1.540), and the concomitant use of diuretics (P<0.001, OR 5.597) were independent risk factors for OXC-induced severe hyponatremia. Age (P=0.001, OR 1.034) and the concomitant use of diuretics (P=0.035, OR 2.222) were independent risk factors for OXC-induced symptomatic hyponatremia. The frequency of OXC-induced symptomatic hyponatremia that was judged to be clinically significant was 2.8% among the total OXC-treated epilepsy patients.

Conclusion: Our study recommended that serum sodium be monitored regularly in patients taking OXC, especially in old age, AED polytherapy or concomitant use of diuretics, to assist in the early recognition of hyponatremia and to increase the awareness of symptoms that might be attributable to this.