Oxcarbazepine-induced Reversible Pancytopenia and Severe Hyponatremia in a Patient with Bipolar Affective Disorder: Two Case Reports

Oxcarbazepine is a widely used mood stabiliser in Bipolar Affective Disorder (BPAD) due to its favourable tolerability compared with carbamazepine. However, it is associated with serious adverse effects, including hyponatraemia and pancytopenia, which require close monitoring. Hereby, the authors present two cases of middle-aged women with BPAD who developed severe hyponatraemia (Na+ <110 mmol/L) and pancytopenia within two to three weeks of oxcarbazepine initiation. Both patients exhibited generalised weakness, dizziness, and fatigue, prompting laboratory evaluations that confirmed marked electrolyte disturbances and haematologic abnormalities. Further investigations ruled out infectious and autoimmune causes. Oxcarbazepine was discontinued, and corrective interventions were initiated, leading to rapid clinical improvement. Sodium levels normalised within three to five days, and haematologic parameters recovered within a week. These cases reinforce the importance of early detection of oxcarbazepine-induced adverse effects, particularly in high-risk populations such as older adults and those with metabolic comorbidities. Although oxcarbazepine remains an effective treatment for BPAD, clinicians must remain vigilant for life-threatening complications. Routine monitoring of serum sodium and blood counts should be an essential part of patient management. Early drug discontinuation in suspected toxicity can prevent serious morbidity and improve patient safety.