Review of carbamazepine-induced hyponatremia.

1. Carbamazepine (CBZ), a commonly prescribed medication in psychiatry and neurology, produces deleterious side effects with an incidence rate ranging from 33-50%; although most of these side effects are mild, transient, and reversible. CBZ-induced hyponatremia is a moderately well described side effect and may be responsible for some of the more highly reported signs and symptoms associated with CBZ adverse effects. 2. Data from case reports and clinical studies are examined to ascertain the characteristics of CBZ-induced hyponatremia. Predisposing risk factors such as: age, dosage/level of CBZ, and polypharmacy have been explored in numerous clinical studies; however, minimal consensus has been found regarding both dosage/level of CBZ and polypharmacy as a predisposing risk factor, whereas age is most probably not a predisposing risk factor in CBZ-induced hyponatremia. 3. Mechanistic studies, both clinical and basic science, also fail to acknowledge the mechanism for the antidiuretic effect of CBZ. The most probable mechanism involves an alteration in either the sensitivity or set point of the osmoreceptor.