Carbamazepine diabetes insipidus

Carbamazepine stimulates antidiuretic hormone activity and has been used for the treatment of neurohypophyseal diabetes insipidus. Carbamazepine induces microsomal enzymes and its metabolism is subject to auto-induction. Frequently occurring adverse effects are sedation, dry mouth, dizziness and gastrointestinal disturbances. Photosensitivity reactions, urticaria and Stevens-Johnson syndrome have been described. The elderly are more prone to mental confusion, cardiac abnormalities and problems due to inappropriate ADH secretion. 

Carbamazepine increases the release of endogenous antidiuretic hormone and can therefore potentiate the antidiuretic effect of desmopressin. Of 103 children with cranial diabetes insipidus included in a retrospective analysis, 10% became hyponatrcmic (76). The risk of hyponatremia was three-fold higher when desmopressin and carbamazepine were given in combination. 

Perlemuter L, Hazard J, Kazatchkine M, Guilhaume B, Bernheim R. Action comparee de la carbamazepine et du clofibrate dans le diabete insipide. Etude de 7 cas. [Comparative action of carbamazepine and clofibrate in diabetes insipidus. Study of 7 cases.] Nouv Presse Med 1975 4(32) 2307-10. 

Chlorpropamide (but not other sulphonylureas) and carbamazepine are effective in partial pituitary diabetes insipidus, i.e. some natural hormone production remains, because they act on the kidney potentiating the effect of vasopressin on the renal tubule. H5q oglycaemia may occur with chlorpropamide. 

In two children with cranial diabetes insipidus, desmopressin requirements fell while they were taking lamotrigine (34). Lamotrigine may act at voltage-sensitive sodium channels and reduce calcium conductance. Both of these mechanisms of action are shared by carbamazepine, which can cause hyponatremia secondary to inappropriate secretion of antidiuretic hormone. 

Carbamazepine is used in the treatment of epilepsy and trigeminal neuralgia. Unlabeled uses include treatment of postherpetic pain syndrome, neurogenic diabetes insipidus, bipolar disorder, alcohol withdrawal, and cocaine dependence. 

Kamiyama T, Iseki K, Kawazoe N, et al. Carbamazepine-induced hyponatremia in a patient with partial central diabetes insipidus. Nephron 1993 64 142-145. 

Carbamazepine and lithium can elevate each other s serum levels (the mechanism is unknown). Toxicity is possible while blood levels are within the normal range, and is partially associated with pre-existing brain abnormalities. The diuretic effect of lithium outweighs the antidiuretic effect of carbamazepine. Carbamazepine does not protect against lithium-induced diabetes insipidus. Lithium can enhance carbamazepine-induced hyponatremia. 

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