Carbamazepine-Associated Hyponatremia

Four cases of CBZ-induced or exacerbated hyponatremia are described in middle-aged to elderly .females. Two cases are remarkable in that the pretreatment sodium levels demonstrate hyponatremia. A return to prior sodium levels was observed upon the discontinuation ofcarbamazepine therapy . No definitioe conclusions can be drawn from these case reports; however, similarities in the cases can be examined asfoiloios: (1) allfo ur women have medical problems, in particular two patients had pre-existing hyponatremia; (2) allfo ur patients were using concurren t medications; (3) all fo ur women presented psychotic. A literature review examines riskf actors, pharmacological mechanism, and the time coursefor CBZ-inducedhyponatremia. Carba mazepine-an iminodiben zyl com pound-was introduced int o clinica l medi cin e in 1962 ( I). Since th at t ime, clinica l stud ies have demonstrat ed ca rbamaz epine (CBZ) to be effec tive in th e treatment of numerou s psychiatric and neu rologic di sorders such as bip olar di sorder (2,3), unipolar depression (3) , gen era lized and psychomotor seizures (4,5) , schizophre nia (6), schizoaffec t ive d isorder (6) , pain syndromes (5,7) , and borderline personality di sorder (8). Addition ally, in 1966 Braunhofer a nd Zicka reported th e an t idiu re tic effect of (C BZ) in neurohypophysial di ab et es insipidus (9). Unfortunat ely, t he a n t id iu re tic effect of C BZ ca n signifi cantly com plica te th e effec t ivene ss of C BZ for th e treatment of psychiatric disorder s by producin g hypon atrem ia. Numerous case re po rts (10-22), studi es (2332), an d two reviews (33,34) have clearly documented th e pr obl e m; however, litt le conse nsus prevail s towards underst anding either th e mech an ism or pr edisposing ca uses for CBZ-induced hyponatremia. In this study, we pr esent four women , middle to elde rly in ag e, who dem onst ra te d hyponatremia after a short duration of C BZ th erapy. Of sig nificance is th e fact that a ll four wom en had pr eviou s medi cal com plica t ions, a nd fu rt hermore, two were hyponatremic prior to CBZ th erap y. Thus, medi cal com plica tions, espec ia lly a prior abnor mality of osmoregula t ion were obse rved to be associa ted with hypon atreWhen th is study was wr itten, Dr. Gandelman a nd Dr. J oh nson wer e resid ent s in th e Dep artment of Psychiat ry, Dr. Dab ora was a th ird yea r med ica l student , a nd Dr. Rib a was an Assist ant Profess or of Psychi atry a t t he U nive rs ity of Conne cti cut. Presently Dr. Gand elm an is an Assist ant Professor of Psych iat ry a t Yale Universi ty, whereas the other Co-authors are pu rsuing ca reers in th eir chose n medi cal specia lt ies.