Effect of cilazapril on hyperdipsia in hemodialyzed patients

To investigate whether angiotensin-converting enzyme inhibitor (ACE-I) potentially alleviates hyperdipsia, the effect of cilazapril on dialysis-associated excessive thirst was studied by evaluating various dipsogenic parameters in patients undergoing chronic hemodialysis (HD) who manifest an excessive interdialysis body weight gain of more than 5%, and show simultaneous severe-to-moderate hyperdipsia. An initial single dose of 1 mg of cilazapril given at the end of the HD session produced a marked improvement in the interdialysis thirst scores and a simultaneous reduction in plasma angiotensin II (AII) concentration due to the inhibition of ACE activity. The interdialysis body weight gain in the cilazapril treatment period was significantly smaller than that in the nontreatment period. None of the other parameters including blood pressure, plasma osmolarity, and serum Na and K concentration were different in the treatment vs. the nontreatment period. The present data help to explain the potential pharmacological action of AII in the physiology of thirst and suggest that cilazapril may effectively alleviate dialysis-associated hyperdipsia at least on some occasions. The mechanism by which ACE-I exerts an antidipsogenic action may, in part, be accounted for by the reduction in plasma concentration of AII, as a result of the ACE inhibition.