Delapril is a prodrug; it is converted into two active metabolites, 5-hydroxy delapril diacid and delapril diacid. These metabolites bind completely to and inhibit angiotensin-converting enzyme (ACE), hence blocking angiotensin I to angiotensin II conversion. The resulting vasodilation prevents the vasoconstrictive effects of angiotensin II. Angiotensin II-induced aldosterone secretion by the adrenal cortex is also decreased by Delapril, leading to increases in excretion of sodium and therefore increases water outflow.