lisinopril

FDA-Approved Indications:

Hypertension (high blood pressure):

• Treatment of hypertension in adults and pediatric patients aged 6 years and older
• May be used as monotherapy or in combination with other antihypertensive agents
• Particularly preferred in patients with diabetes, chronic kidney disease (CKD), or heart failure

Heart failure (HF):

• Adjunctive therapy for the management of heart failure with reduced ejection fraction (HFrEF, EF <40%) in patients not adequately controlled on diuretics and digitalis
• Reduces mortality, hospitalizations for heart failure, and symptoms (ATLAS trial: lisinopril 32.5–35 mg vs. 2.5–5 mg — high-dose reduced all-cause mortality by 8% and hospitalizations by 24%)

Acute myocardial infarction (AMI):

• Reduces mortality in hemodynamically stable patients within 24 hours of an acute MI
• GISSI-3 trial: lisinopril started within 24 hours of AMI reduced 6-week mortality by 11% and the combined endpoint of death/severe LV dysfunction by 17%
• Continue for at least 6 weeks; long-term therapy is recommended in patients with reduced EF or heart failure

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Guideline-Recommended Uses (off-label but strongly supported):

• Diabetic nephropathy / CKD proteinuria: First-line therapy (JNC 8, ADA, KDIGO guidelines) — reduces proteinuria and slows GFR decline in both type 1 and type 2 diabetes. EUCLID trial: lisinopril reduced urinary albumin excretion by 49% in normotensive type 1 diabetics
• Secondary stroke prevention: Recommended in combination with a thiazide diuretic (PROGRESS trial used perindopril + indapamide; class effect applies to lisinopril)
• Left ventricular dysfunction (asymptomatic): Recommended post-MI to prevent progression to symptomatic heart failure (EF <40%)
• Hypertensive urgency/emergency: Oral lisinopril can be used for non-emergency blood pressure reduction (not for hypertensive emergency requiring IV therapy)

Dosing by Indication

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Renal Dosing (Critical — Lisinopril is renally cleared)

Lisinopril is removed by hemodialysis — supplemental dosing after dialysis sessions may be needed. Monitor blood pressure and potassium closely in patients with CKD.

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Administration Instructions

• Take once daily at the same time each day, with or without food
• Tablets may be crushed if swallowing is difficult
• If a dose is missed: take as soon as remembered unless it is almost time for the next dose; do not double doses
• Blood pressure-lowering effect begins within 1 hour, peaks at 6–8 hours, and lasts 24 hours
• Full antihypertensive effect may take 2–4 weeks — do not increase dose more frequently than every 2 weeks
• For heart failure: titrate slowly (every 2 weeks) to target dose of 20–40 mg; do not rush titration in patients with low blood pressure or impaired renal function

Lisinopril is a competitive inhibitor of angiotensin-converting enzyme (ACE), the enzyme responsible for converting angiotensin I (an inactive precursor) to angiotensin II (a potent vasoconstrictor). By blocking this conversion, lisinopril disrupts the renin-angiotensin-aldosterone system (RAAS) at a critical step.

Step-by-step mechanism:

1. ACE inhibition and angiotensin II reduction ACE (also called kininase II) cleaves the C-terminal dipeptide from angiotensin I to produce angiotensin II. Lisinopril binds tightly to the ACE active site (containing a zinc ion), preventing this cleavage. With less angiotensin II produced, the powerful vasoconstrictor effect on arterioles is removed, causing vasodilation and blood pressure reduction.

2. Aldosterone suppression Angiotensin II normally stimulates the adrenal cortex to release aldosterone, which causes sodium and water retention (raising blood volume and pressure) and potassium excretion. By reducing angiotensin II, lisinopril suppresses aldosterone, leading to modest natriuresis (sodium excretion) and potassium retention — the mechanism behind ACE inhibitor-associated hyperkalemia.

3. Bradykinin accumulation ACE also degrades bradykinin (a vasodilatory peptide). By inhibiting ACE, lisinopril allows bradykinin to accumulate. Bradykinin stimulates nitric oxide (NO) and prostaglandin release, contributing to vasodilation and the antihypertensive effect. However, bradykinin accumulation in the airways is also the primary cause of the ACE inhibitor dry cough (affects 10–20% of patients, up to 40% in Asian populations) and, rarely, angioedema.

4. Cardiac and renal remodeling prevention Beyond blood pressure lowering, reduced angiotensin II activity prevents pathological cardiac remodeling (hypertrophy, fibrosis) in heart failure and post-MI patients, and reduces glomerular efferent arteriole constriction in the kidney — lowering intraglomerular pressure and reducing proteinuria.

Key clinical trial evidence:

• ALLHAT (2002): Largest antihypertensive trial (n=33,357) — lisinopril equivalent to chlorthalidone and amlodipine for primary CHD endpoint; slightly inferior for stroke prevention in Black patients (where ACE inhibitors are less effective as monotherapy)
• GISSI-3 (1994): Lisinopril started within 24h of AMI — 11% reduction in 6-week mortality; 17% reduction in death/severe LV dysfunction
• ATLAS (1999): High-dose lisinopril (32.5–35 mg) vs. low-dose (2.5–5 mg) in HFrEF — 8% reduction in all-cause mortality, 24% reduction in hospitalizations
• EUCLID (1997): Lisinopril in normotensive type 1 diabetics — 49% reduction in urinary albumin excretion, slowing of nephropathy progression

Potassium-Elevating Agents (hyperkalemia risk):

Blood Pressure-Lowering Agents (additive hypotension):

• Diuretics: additive BP lowering; risk of first-dose hypotension. Reduce diuretic dose or hold for 2–3 days before starting lisinopril
• Other antihypertensives (calcium channel blockers, beta-blockers, alpha-blockers): additive effect; generally beneficial but monitor for hypotension
• Phosphodiesterase-5 inhibitors (sildenafil, tadalafil): additive hypotension, especially in heart failure patients

NSAIDs and COX-2 Inhibitors: NSAIDs (ibuprofen, naproxen, celecoxib) reduce the antihypertensive effect of lisinopril (by blocking prostaglandin-mediated vasodilation) and increase the risk of acute kidney injury and hyperkalemia. Avoid regular NSAID use in patients on lisinopril; use acetaminophen for pain management when possible.

Lithium: Lisinopril reduces renal lithium clearance, potentially causing lithium toxicity. Monitor lithium levels closely when starting, adjusting, or stopping lisinopril. Symptoms of lithium toxicity: tremor, confusion, ataxia, nausea.

Dual RAAS Blockade (ACE inhibitor + ARB or aliskiren): Combining lisinopril with an ARB (losartan, valsartan) or aliskiren increases the risk of hypotension, hyperkalemia, and renal impairment without additional cardiovascular benefit (ONTARGET trial). Avoid dual RAAS blockade except in specific circumstances (e.g., HFrEF with intolerance to aldosterone antagonists under specialist supervision).

Sacubitril/Valsartan (Entresto): Do not administer within 36 hours of switching to or from sacubitril/valsartan — risk of angioedema due to combined neprilysin inhibition (which further elevates bradykinin).

Gold (sodium aurothiomalate): Rare nitritoid reactions (facial flushing, nausea, hypotension) reported with concurrent ACE inhibitor use.

Pregnancy — Contraindicated (all trimesters): Lisinopril is contraindicated throughout pregnancy. During the 2nd and 3rd trimesters, ACE inhibitors can cause fetal renal dysfunction, oligohydramnios, fetal limb contractures, craniofacial deformities, hypoplastic lung development, and neonatal death. Even 1st trimester exposure has been associated with cardiovascular and CNS malformations. Discontinue immediately when pregnancy is detected. Women of childbearing potential should use effective contraception. If blood pressure control is needed during pregnancy, use methyldopa, labetalol, or nifedipine.

Lactation: It is unknown whether lisinopril is present in human breast milk. Because of the potential for serious adverse reactions in nursing infants (particularly hypotension and renal effects), breastfeeding is not recommended during lisinopril therapy. Consider alternative antihypertensives compatible with breastfeeding (e.g., nifedipine, labetalol).

Pediatric Use (≥6 years): FDA-approved for hypertension in pediatric patients aged 6 years and older weighing ≥20 kg. Starting dose: 0.07 mg/kg once daily (maximum 5 mg). Maximum dose: 0.61 mg/kg/day or 40 mg/day. Not studied in children <6 years or in children with GFR <30 mL/min/1.73 m². Monitor blood pressure, renal function, and potassium.

Geriatric Use (≥65 years): No dose adjustment required based on age alone. However, elderly patients are more susceptible to first-dose hypotension (reduced baroreceptor sensitivity, often volume-depleted from diuretics). Start at 5–10 mg and titrate slowly. Monitor renal function and potassium more frequently as renal function declines with age.

Renal Impairment: Dose adjustment required (see Dosage section). Lisinopril is renally cleared — plasma levels increase proportionally with decreasing GFR. Monitor creatinine, BUN, and potassium closely. In dialysis patients, lisinopril is removed during hemodialysis sessions; supplemental dosing may be needed.

Hepatic Impairment: No dose adjustment required — lisinopril is not hepatically metabolized. However, severe hepatic impairment with ascites may cause secondary hyperaldosteronism and volume overload that affects response to lisinopril.

Black/African American patients: ACE inhibitors, including lisinopril, are generally less effective as monotherapy for blood pressure lowering in Black patients compared to calcium channel blockers or thiazide diuretics (ALLHAT finding). However, lisinopril is still recommended in Black patients with diabetes, CKD with proteinuria, or heart failure, where the RAAS-specific benefits are important. Consider combining with a calcium channel blocker or thiazide diuretic for adequate BP control. Black patients also have 3–4× higher risk of ACE inhibitor-associated angioedema.