Dose-response relations in drug-induced inappropriate secretion of ADH: effects of clofibrate and carbamazepine.

The effect of different doses of clofibrate and carbamazepine on water metabolism was compared in a patient with psychogenic polydipsia. A definite relationship was found between the doses of both drugs and the antidiuretic effect. Daily 2--4 g clofibrate was ineffective, but 6--8 g induced the syndrome of inappropriate secretion of ADH. 600 mg carbamazepine a day induced a marked antidiuretic response which could be further augmented by administering daily 1200--1800 mg. The discrepancy between the effective "hypolipidemic" and "antidiuretic" dose of clofibrate may perhaps explain the lack of reports on water intoxication induced by this agent, despite of its entensive use in clinical practice.