DIFFERENTIAL-EFFECTS OF ORAL LOSARTAN AND ENALAPRIL ON LOCAL VENOUS AND SYSTEMIC PRESSOR-RESPONSES TO ANGIOTENSIN-I AND ANGIOTENSIN-II IN HEALTHY-MEN

This double-blind, placebo-controlled crossover study was designed to differentiate the pharmacodynamic effects of the angiotensin II recept or antagonist losartan from the angiotensin converting enzyme inhibito r enalapril. Effects of placebo, enalapril (10 mg), and losartan (20 a nd 100 mg) on local venous and systemic presser responses to angotensi n I and II were compared in eight healthy male subjects. Treatments we re administered orally approximately 4 hours before agonist infusions into a dorsal hand vein. Local changes in hand vein diameter and syste mic blood pressure were monitored during the infusions. The 100 mg dos e of losartan attenuated local venoconstrictor and systemic presser re sponses to angiotensin I and II, In contrast, enalapril blocked only r esponses to angiotensin I. Both losartan and enalapril increased plasm a renin concentration compared with placebo. These results are consist ent with direct antagonism of angiotensin II receptors by losartan and with indirect effects of enalapril through inhibition of angiotensin converting enzyme.