Mechanism of action
Lisinopril competitively inhibits angiotensin-converting enzyme (ACE), the enzyme responsible for converting angiotensin I to angiotensin II. By blocking this conversion, lisinopril reduces circulating levels of angiotensin II, a potent vasoconstrictor. This leads to vasodilation and decreased blood pressure.
Reduction in angiotensin II also decreases aldosterone secretion from the adrenal cortex, resulting in decreased sodium and water retention and increased potassium retention. ACE is identical to kininase II, the enzyme that degrades bradykinin. Inhibition of ACE leads to bradykinin accumulation, which contributes to vasodilation but also causes the characteristic dry cough and angioedema seen with ACE inhibitors.
The overall hemodynamic effects include decreased systemic vascular resistance, reduced preload and afterload, and decreased cardiac workload. These effects make ACE inhibitors particularly beneficial in heart failure and post-myocardial infarction remodeling.
- Lisinopril inhibits ACE (identical to kininase II), causing bradykinin accumulation responsible for dry cough and angioedema
- Unlike most ACE inhibitors, lisinopril is not metabolized hepatically and is excreted unchanged in urine
- ACE inhibitors are contraindicated in pregnancy (cause oligohydramnios, renal failure, skull hypoplasia in second/third trimester)
- An acute creatinine rise up to 30% after starting lisinopril is acceptable; larger rises suggest bilateral renal artery stenosis
- ACE inhibitors cause hyperkalemia by reducing aldosterone secretion; avoid concurrent potassium-sparing diuretics
- Dry cough occurs in 5-15% of patients and is not dose-dependent; switching to an ARB resolves this
- Angioedema risk is higher in African American patients and can occur at any time during therapy
- First-line agents for hypertension with diabetes or CKD due to renoprotective effects independent of BP lowering
Indications
Lisinopril is FDA-approved for multiple cardiovascular conditions:
Hypertension: Lisinopril is a first-line agent for essential hypertension, particularly in patients with diabetes or chronic kidney disease, as it provides renal protective effects.
Heart failure: Used in patients with reduced ejection fraction (HFrEF) to improve symptoms, reduce hospitalizations, and decrease mortality. ACE inhibitors are cornerstone therapy in the management of systolic heart failure.
Acute myocardial infarction: Initiated within 24 hours of acute MI in hemodynamically stable patients to improve survival and reduce adverse remodeling. Provides long-term cardioprotection.
Diabetic nephropathy: Slows progression of proteinuria and preserves renal function in diabetic patients, independent of blood pressure effects.
Chronic kidney disease: Reduces proteinuria and slows progression of kidney disease, especially in patients with proteinuria greater than 300 mg/day.
Pharmacokinetics
Lisinopril exhibits unique pharmacokinetic properties compared to other ACE inhibitors:
Absorption: Oral bioavailability is approximately 25-30% and is not affected by food. Peak plasma concentrations occur within 6-8 hours.
Distribution: Lisinopril is hydrophilic and does not cross the blood-brain barrier or readily penetrate lipid membranes. It does not bind significantly to plasma proteins.
Metabolism: Lisinopril is not metabolized and is excreted unchanged in the urine. This is clinically important as it does not undergo hepatic metabolism, making it safer in patients with liver disease and reducing potential for drug interactions.
Elimination: Entirely eliminated by renal excretion with a half-life of approximately 12 hours. Dose adjustment is required in renal impairment. In patients with creatinine clearance below 30 mL/min, significant dose reduction is necessary.
Time to steady state: Requires 2-3 days to reach steady-state plasma concentrations. Maximum blood pressure reduction may take 2-4 weeks of therapy.
Adverse effects
ACE inhibitors have a characteristic adverse effect profile that is frequently tested:
Common adverse effects
- Dry cough (5-15%): The most common reason for discontinuation. Caused by bradykinin accumulation in the bronchial tree. Not dose-dependent and may occur weeks to months after initiation. Resolves within 1-4 weeks of discontinuation.
- Hypotension: Especially with first dose or in volume-depleted patients. More common in heart failure patients or those on diuretics.
- Hyperkalemia: Results from decreased aldosterone. Risk is increased with concurrent use of potassium-sparing diuretics, potassium supplements, or NSAIDs.
- Dizziness and fatigue: Related to blood pressure reduction.
- Acute kidney injury: May cause transient elevation in serum creatinine, especially in patients with bilateral renal artery stenosis or severe heart failure. An increase up to 30% from baseline is generally acceptable.
Serious adverse effects
- Angioedema (0.1-0.7%): Potentially life-threatening swelling of the face, lips, tongue, and larynx due to bradykinin accumulation. More common in African American patients. Occurs most frequently within the first month but can happen at any time. Requires immediate discontinuation.
- Fetal toxicity: ACE inhibitors are contraindicated in pregnancy (Category D). Exposure during second and third trimesters can cause oligohydramnios, fetal hypotension, renal failure, skull hypoplasia, and death.
- Hepatotoxicity: Rare but may cause cholestatic jaundice progressing to hepatic necrosis.
- Neutropenia/agranulocytosis: Rare but serious, particularly in patients with renal impairment or collagen vascular disease.
Contraindications and warnings
Absolute contraindications
- Pregnancy: ACE inhibitors cause fetal toxicity and are contraindicated in all trimesters. Women of childbearing age should use effective contraception.
- History of angioedema: Previous angioedema with ACE inhibitor use or hereditary/idiopathic angioedema.
- Bilateral renal artery stenosis: Can precipitate acute renal failure by preventing compensatory efferent arteriolar constriction.
- Concurrent aliskiren use in diabetic patients: Increases risk of renal impairment, hyperkalemia, and hypotension.
Warnings and precautions
- Renal function monitoring: Check serum creatinine and potassium within 1-2 weeks of initiation and after dose increases. An increase in creatinine up to 30% is acceptable and does not require discontinuation.
- Volume depletion: Correct before initiating therapy to reduce risk of hypotension.
- Aortic stenosis or hypertrophic cardiomyopathy: Use with caution as vasodilation may reduce cardiac output.
- Collagen vascular disease: Increased risk of neutropenia; monitor white blood cell count.
- Surgery: May enhance hypotensive effects of anesthesia.
- Hyperkalemia risk: Avoid potassium supplements and potassium-sparing diuretics unless serum potassium is low.
Drug interactions
Several clinically significant drug interactions occur with lisinopril:
Potassium-sparing diuretics and potassium supplements: Spironolactone, amiloride, triamterene, and potassium chloride significantly increase hyperkalemia risk. Monitor potassium closely if concurrent use is necessary.
NSAIDs and COX-2 inhibitors: Reduce antihypertensive efficacy by inhibiting prostaglandin-mediated vasodilation. Increase risk of acute kidney injury and hyperkalemia, especially in elderly or volume-depleted patients.
Diuretics: Loop and thiazide diuretics may cause excessive hypotension, particularly with first dose. However, this combination is often therapeutically beneficial.
Lithium: ACE inhibitors reduce lithium clearance, increasing risk of lithium toxicity. Monitor lithium levels closely.
Aliskiren: Concurrent use increases risk of hyperkalemia, hypotension, and renal dysfunction. Contraindicated in diabetic patients.
Sacubitril: Do not administer within 36 hours of switching between neprilysin inhibitors and ACE inhibitors due to increased angioedema risk.
Antidiabetic agents: ACE inhibitors may enhance hypoglycemic effects of insulin and oral hypoglycemic agents.
Gold sodium thiomalate: Rare nitritoid reactions (facial flushing, nausea, vomiting, hypotension) have been reported with concurrent injectable gold and ACE inhibitors.
Clinical pearls
First-dose hypotension: Most pronounced in volume-depleted patients or those on high-dose diuretics. Consider holding diuretic 2-3 days before initiation or starting with a lower dose in high-risk patients.
Cough management: If dry cough develops, confirm it is not related to heart failure first. Switching to an angiotensin receptor blocker (ARB) eliminates cough in most patients as ARBs do not inhibit bradykinin degradation.
Acceptable creatinine rise: An acute rise in serum creatinine up to 30% above baseline after ACE inhibitor initiation is hemodynamically mediated and acceptable. Greater increases or progressive rises warrant evaluation for renal artery stenosis or volume depletion.
Renal protection: The renoprotective effects of ACE inhibitors in diabetic and non-diabetic kidney disease are partially independent of blood pressure reduction, mediated by reducing intraglomerular pressure.
Heart failure titration: In heart failure, titrate to target doses used in clinical trials rather than stopping at blood pressure targets. Patients may tolerate systolic blood pressure in the 90-100 mmHg range.
African American patients: ACE inhibitors are less effective as monotherapy in African American hypertensive patients due to lower baseline renin activity. Often require combination with a calcium channel blocker or thiazide diuretic. This population also has higher angioedema risk.
Pregnancy testing: Given the serious teratogenic effects, ensure adequate contraception or pregnancy testing in women of childbearing potential before initiating therapy.
Post-MI timing: In acute MI, initiate within 24 hours if the patient is hemodynamically stable (no hypotension or cardiogenic shock). Provides mortality benefit and reduces adverse remodeling.
Hyperkalemia management: Mild hyperkalemia (5.5-6.0 mEq/L) can often be managed by reducing dose, stopping potassium supplements, or dietary modification rather than discontinuing the ACE inhibitor entirely, especially in heart failure patients who derive significant benefit.
ACE inhibitor adverse effects - CAPTOPRIL: Cough, Angioedema, Potassium elevation, Teratogen, Orthostatic hypotension, Proteinuria (actually reduces it, but helps remember renal effects), Rash, Increased renin, Lower angiotensin II
Practice questions
1. A 58-year-old man with type 2 diabetes and hypertension is started on lisinopril. Two weeks later, his blood pressure is well controlled, but he develops a persistent dry cough that is worse at night. Physical examination is otherwise unremarkable, and chest X-ray shows no abnormalities. What is the most appropriate next step in management?
2. A 65-year-old woman with heart failure is started on lisinopril 5 mg daily. Her baseline serum creatinine is 1.2 mg/dL. One week after initiation, her creatinine is 1.5 mg/dL (25% increase), but she feels well with improved dyspnea. Blood pressure is 118/76 mmHg, and potassium is 4.8 mEq/L. What is the most appropriate management?
3. A 52-year-old African American man presents to the emergency department with sudden onset of lip and tongue swelling 6 hours after taking his second dose of lisinopril, which was started for hypertension. He has mild difficulty swallowing but no stridor or respiratory distress. Which of the following best explains the mechanism of this reaction?
Frequently asked questions
How does lisinopril work?
Lisinopril works by inhibiting angiotensin-converting enzyme (ACE), which blocks the conversion of angiotensin I to angiotensin II. This reduces vasoconstriction and aldosterone secretion, lowering blood pressure and decreasing sodium and water retention. By inhibiting ACE (which is identical to kininase II), lisinopril also prevents bradykinin breakdown, contributing to vasodilation but also causing side effects like dry cough.
What are the side effects of lisinopril?
The most common side effects include dry cough (5-15%), dizziness, hypotension, and fatigue. Serious adverse effects include angioedema (swelling of face, lips, tongue), hyperkalemia (elevated potassium), and acute kidney injury. Lisinopril can cause fetal toxicity and is contraindicated in pregnancy. The dry cough is caused by bradykinin accumulation and is not dose-dependent, often requiring switching to an ARB if bothersome.
Is lisinopril a controlled substance?
No, lisinopril is not a controlled substance. It is a prescription medication used to treat hypertension and heart failure but has no abuse potential and is not regulated under the Controlled Substances Act. It requires a prescription because it can cause serious adverse effects like angioedema, hyperkalemia, and kidney injury that require medical monitoring.
Lisinopril vs losartan — what is the difference?
Lisinopril is an ACE inhibitor while losartan is an angiotensin receptor blocker (ARB). Both reduce angiotensin II effects but through different mechanisms. Lisinopril blocks angiotensin II formation, while losartan blocks its action at receptors. The key clinical difference is that lisinopril causes dry cough and angioedema more frequently because it increases bradykinin levels, while losartan does not affect bradykinin. ARBs are often used when patients cannot tolerate ACE inhibitor cough.
Can lisinopril cause kidney damage?
Lisinopril typically protects kidneys long-term, especially in diabetes and chronic kidney disease, by reducing intraglomerular pressure. However, it can cause acute, usually reversible increases in creatinine, particularly in bilateral renal artery stenosis or severe volume depletion. A creatinine rise up to 30% from baseline is generally acceptable. In bilateral renal artery stenosis, lisinopril can precipitate acute renal failure by preventing compensatory efferent arteriolar vasoconstriction.
Conditions it is used for
Related drugs
Sources and further reading
DailyMed (FDA labels)StatPearls (NCBI Bookshelf)MedlinePlusWHO ATC/DDD index: C09AA03
Educational content for medical students, prepared by the WhiteCoat Pro editorial team with AI assistance; every page is reviewed by a second AI model for factual errors. It is not medical advice and does not replace the product label, local guidelines or a clinician.