- Lisinopril is an angiotensin converting enzyme (ACE) inhibitor. Angiotensin is a chemical that is made by the body continuously. Angiotensin narrows blood vessels and thereby maintains (elevates) blood pressure. When the enzyme is blocked by lisinopril, angiotensin cannot be converted into its active form. As a result, blood pressure is lowered. Lisinopril is a drug that has been approved for use by the U.S. Food and Drug Administration (FDA) and health authorities for the treatment of high blood pressure and heart failure.