用量依存性のラモトリギン誘発性陰茎硬直症の双極性障害患者における一症例

Priapism is defined as a prolonged and persistent erection of the penis without sexual stimulation. Priapism can be caused either by organic factors or as a side effect of drugs. Mood stabilizer induced priapism has been reported less frequently compared to other psychotropic agents. This paper reports a case of lamotrigine induced priapism.

A 24-year-old patient had a diagnosis of bipolar disorder for 4 years. He had been treated with lamotrigine (200 mg/day), sertraline (25 mg/day) and risperidone (2 mg/day) for last year. He developed priapism one week after the lamotrigine dose was increased to 300 mg/day during a depressive episode. Priapism improved the day after the lamotrigine dose was reduced to 250 mg/day.

Epilepsy patients with lamotrigine-induced sexual dysfunction or priapism have been reported previously. In this case, a patient diagnosed with bipolar disorder developed dose dependent lamotrigine-induced priapism. In clinical practice, the possible risk of priapism should be taken into consideration in patients using lamotrigine, especially during dose increases.