COMPARISON OF THE ORAL ANGIOTENSIN-II RECEPTOR ANTAGONIST UP-269-6 OR ENALAPRIL 20 MG ON BLOOD-PRESSURE AND NEUROHORMONAL EFFECTS IN SALT-DEPLETE MAN

We compared the response of the oral angiotensin II (Ang II) receptor antagonist (ARA) UP 269-6 with an angiotensin converting enzyme inhibitor (ACEI) enalapril 20 mg or placebo, during salt depletion in normal men. We also evaluated safety and tolerability. Sixteen healthy, normotensive male volunteers followed a standardised salt-depletion regimen for 3 days before each study day. Seven different doses of UP 269-6 (5, 10, 20, 40, 80, 120 and 180 mg) were administered double blind in a four-panel dose escalation, with enalapril and placebo randomised within each panel. Supine and erect blood pressure (BP) and heart rate (HR); serum and urinary electrolytes; plasma active renin (PAR), aldosterone, and Ang II were measured at intervals. Urinary electrolytes and aldosterone were measured for the 24 h before dosing and for 24 h after dosing. Dizziness and light-headedness on standing were reported after UP 269-6 at higher doses. Enalapril caused one episode of symptomatic postural hypotension. No other drug-related adverse events (AE) were noted. There was a dose-related decrease in supine and erect systolic and diastolic BP (SEP, DBP) with UP 269-6 at greater than or equal to 40 mg, with no change in HR. Based on the maximal decrease in mean arterial pressure (MAP), UP 269-6 at 180 mg had an effect largely comparable to that of enalapril 20 mg. There was a dose-related increase in PAR with UP 269-6. Although this was greater with UP 269-6 180 mg than with enalapril, serum and 24-h urinary aldosterone suppression was greater with enalapril than with any dose of UP 269-6. There was a dose-related increase in Ang II, with the expected decrease after enalapril. Our results indicate a clear BP and hormonal dose response relation for UP 269-6. The BP-lowering effect is observed starting with the 40-mg dose. Based on the maximal decrease in MAP, UP 269-6 180 mg is largely comparable to enalapril 20 mg.