EFFECTS OF CICLETANINE ON THE URINARY-EXCRETION OF PROSTANOIDS AND KALLIKREIN, AND ON RENAL-FUNCTION IN MAN

The effects of cicletanine, a new antihypertensive agent, on the prost aglandin-kallikrein system and the renin-angiotensin system were studi ed. A single oral dose of 200 mg cicletanine or placebo was administer ed to 9 healthy male volunteers, with samples of blood and urine obtai ned before and 2 hours after drug administration. Cicletanine increase d the urine flow, urinary excretion of sodium, and fractional excretio n of sodium by 47%, 115%, and 104%, respectively. While the excretion of 6-keto-prostaglandin-F1alpha was enhanced significantly, urinary ex cretion of thromboxane-B2, prostaglandin-E2, and kallikrein were uncha nged. Cicletanine also did not alter plasma renin activity, plasma ald osterone concentration, or creatinine clearance. These observations su ggest that cicletanine may suppress sodium reabsorption at the nephron , and it may stimulate prostacyclin generation with no effect on that of thromboxane-A2. Thus cicletanine may be beneficial in the managemen t of cardiovascular disorders in which the equilibrium between prostac yclin and thromboxane is disturbed.