A phosphinic acid-containing angiotensin-converting enzyme (ACE) inhibitor with antihypertensive activity. As an ester prodrug, fosinopril is hydrolysed by esterases to its active metabolite fosinoprilat. Fosinoprilat specifically and competitively inhibits angiotensin-converting enzyme thereby decreasing the formation of the potent vasoconstrictor angiotensin II, resulting in diminished vasopressor activity. In addition, angiotensin II-mediated aldosterone secretion by adrenal cortex is decreased, which results in a decrease of sodium retention and an increase in water outflow.