NCIt definition : The hydrochloride salt form of spirapril, a prodrug and non-sulfhydryl angiotensin
converting enzyme (ACE) inhibitor with antihypertensive activity. Spirapril is converted
in the body to its active metabolite spiraprilat. Spiraprilat competitively binds
to and inhibits ACE, thereby blocking the conversion of angiotensin I to angiotensin
II. This prevents the potent vasoconstrictive actions of angiotensin II and results
in vasodilation. Spirapril also decreases angiotensin II-induced aldosterone secretion
by the adrenal cortex, which leads to an increase in sodium excretion and subsequently
increases water outflow.;