Oxcarbazepine and hyponatremia

Abstract

Purpose: Hyponatremia is one of the most common adverse effectsin patientstreated with oxcarbazepine (OXC). Differentrisk factorsfor OXC-induced hyponatremia have been described (e.g., age, dosage, combination with other drugs, female gender). During our clinical practice, we have noticed that longer duration of treatment with OXC could be associated with higher risk of hyponatremia, therefore, in this study we aimed to evaluate the factors that may increase risk of OXC - induced hyponatremia. Methods: Thirty-one adult patients with epilepsy who received OXC monotherapy or combination therapy were retrospectively included in this study. The following data were collected: demographic information (gender, age), clinical characteristics (OXC, sodium concentration, duration of OXC therpy, comedications). Individuals who had another condition that could potentially affect sodium levels (e.g., pregnancy, use of diuretics, adrenal gland insufficiency and hypopituitarism) were excluded. Hyponatremia was defined < 136mmol/l. Results: The data of 31 patients was analyzed (64.5% females [n = 20]; median age 50 years with a range of 20- 77 years). The daily dose of OXC ranged from 300 to 1950 mg and its median was 1200 mg. The average serum concentration of OXC was 15.4 ±6.3 μg/ml (reference range 10-35 μg/ml). OXC as monotherapy used 8 (25.8 %) participants. Median duration of OXC therapy was 8 years with a range from 1 to 22 years. The majority of patients (61.3%, n = 19) developed hyponatremia. Binary logistic regression analysis demonstrated that each year of therapy with OXC increased hyponatremia risk 1.403 times (OR- 1.403, 95% Cl 1.048- 1.879, p = 0.023) whereas other factors (gender, age, polypharmacy, OXC dosage and serum concentration) did not show significant association with the development of hyponatremia. Conclusion: Longer duration of treatment with oxcarbazepine is associated with a higher risk of hyponatremia.