Psychopharmacology Recurrent hypomania induced by lamotrigine

Lamotrigine is an anticonvulsant agent used in the treatment of epilepsy and bipolar affective disorder. Many clinical trials indicate that lamotrigine is helpful in the acute phase of bipolar disorder. Lamotrigine is used as an adjuvant mood stabilizer and there are case reports showing that it induces mania and hypomania. Here we present a case of lamotrigine-induced recurrent hypomania at minimum increase of dose with maintenance therapy with lithium. A 42-year-old male with bipolar disorder raised complaints of unhappiness and fatigue lasting more than one year. During the follow up he had lithium therapy, after depressive symptoms and then he was given lamotrigine 25 mg/day. When the dose was increased to 50 mg/day, he had euphoria so the dose was decreased to 25 mg/day again. In his next admission, the lamotrigine dose is again increased to 37.5 mg/day and he again complained for the same euphoric and hypomanic phenomena. The dose was again decreased to 25 mg/day with which he felt comfortable. He was on continuous lithium prophylaxis during these follow-ups and although blood lithium level was on the therapeutic range, this did not prevent the hypomania induced by lamotrigine, when the dose was titrated above 25 mg/day. Now the patient is under lithium 1200 mg/day with lamotrigine 25 mg/day and he is symptom free. Our case report emphasizes severe manic/hypomanic switches that lamotrigine may induce. Caution should be taken in case of lamotrigine prescription even when it is given at very small doses.