Pharmacologic studies in Bartter's syndrome: effect of DDAVP and indomethacin on renal concentrating operation. Part II.

We have investigated the effect of indomethacin and DDAVP on water excretion in a patient with familial Bartter's syndrome in whom urinary concentration was impaired during ad libitum fluid intake without any decrease in maximal concentrating ability. In response to indomethacin urine osmolality and free water reabsorption increased, simultaneously with the decrease in the excretion of prostaglandin E2. The indomethacin induced improvement was however less than that obtained after DDAVP with or without indomethacin. The results can be interpreted on the basis of either a direct "vasopressin-like" action of indomethacin or abolishment of the peripheral vasopressin--prostaglandin interaction. The clinical implication is that the theoretical possibility of indomethacin-induced inappropriate ADH syndrome should be borne in mind when a patient is treated with this drug on a long term basis.