Carbamazepineによる低Na血症

Carbamazepine Induced Hyponatremia

I．はじめに

　Carbamazepine（CBZ：商品名テグレトール）は抗けいれん剤や三叉神経痛・頑痛症などの疼痛発作抑制剤として使用する頻度が多い．CBZの副作用としてめまい・立ち眩み・集中力低下はしばしば経験する．しかしCBZはsyndrome of inap-propriate antidiuretic hormone（SIADH）を生じうる薬剤でもある．1980年代まではCBZによる低Na血症の報告が散見されるが^4,5,9,10），最近ではその報告はほとんどない．今回われわれはCBZが原因となった低Na血症の2例を経験したので報告する．

Carbamazepine (CBZ) is a drug which can induce the syndrome of inappropriate antidiuretic hormone(SIADH). Until 1980's, there were reports regarding CBZ-induced SIADH, but it is rarely reported thesedays. We here report two cases of CBZ-induced SIADH. Hyponatremia in these cases was rapidly im-proved by withdrawal of administration of CBZ. According to the previous reports, the rate of hyponatre-mia in patients receiving CBZ is not small. It ranges from 4.8% to 31%. As CBZ is frequently used for pa-tients with epilepsy and neuralgia, not only their blood CBZ concentration but also their serum Na levelshould be monitored.