Lisinopril

Introduction Overview

Generic Name

lisinopril

Brand Name

Zestril

Dosage Form

oral tablet (2.5 mg; 5 mg; 10 mg; 20 mg; 30 mg; 40 mg)

Drug Class

Angiotensin Converting Enzyme Inhibitors (ACE inhibitors)

Pharmacokinetics

Absorption:
Lisinopril is well absorbed after oral administration with bioavailability estimated around 25%. Peak plasma concentrations are typically reached within 7 hours after a single dose. Food does not significantly affect the absorption of lisinopril, so it can be administered without regard to meals, providing dosing flexibility for patients in clinical practice. The extent of absorption may vary with gastrointestinal pH and motility, but overall oral bioavailability is consistent. The rate of absorption allows for once-daily dosing in the majority of indications.

Distribution:
After absorption, lisinopril distributes primarily into the extracellular fluid space. Plasma protein binding for lisinopril is low, approximately 25%, which facilitates its availability at the target sites such as the vascular endothelium and kidney. The volume of distribution ranges from 0.12 to 0.17 L/kg, indicating a moderate distribution primarily in plasma and extracellular compartments. Lisinopril does not cross the blood-brain barrier easily, minimizing central nervous system side effects.

Metabolism:
Lisinopril differs from some other ACE inhibitors in that it is not metabolized by the liver. It remains largely unmetabolized throughout its pharmacokinetic course, being excreted unchanged in urine. This lack of hepatic metabolism reduces potential drug-drug interactions and makes lisinopril suitable for patients with hepatic impairment. Studies confirm minimal or no metabolites were detected in plasma or urine, reinforcing its direct renal elimination pathway.

Elimination:
Lisinopril is primarily eliminated unchanged by the kidneys through glomerular filtration and renal tubular secretion. The elimination half-life ranges from 12 to 13 hours in patients with normal renal function, supporting once-daily dosing schedules. In patients with impaired renal function, clearance is markedly reduced and half-life prolonged, necessitating dosage adjustments based on creatinine clearance. Approximately 50% of the administered dose is recovered unchanged in the urine within 24 hours. Hemodialysis eliminates less than 20% of lisinopril, making supplemental dosing after dialysis generally unnecessary. Therefore, renal function assessment is crucial for safe and effective dosing of lisinopril.

Dosage Forms

Available Dosage Forms:
Zestril is available exclusively as oral tablets with the following strengths: 2.5 mg, 5 mg, 10 mg, 20 mg, 30 mg, and 40 mg. The tablets contain lisinopril as the active ingredient along with inactive substances such as calcium phosphate, magnesium stearate, mannitol, starch, and varying ferric oxides as colorants depending on the strength. This formulation allows for precise dosing increments to meet individualized patient needs.

Dosages for Adults and Adolescents:
- Hypertension: The initial adult dose is typically 10 mg orally once daily, with a lower starting dose of 5 mg for patients receiving concurrent diuretic therapy. Maintenance dosing generally ranges from 20 to 40 mg once daily, with a maximum dose of 80 mg per day although doses beyond 40 mg have not shown additional efficacy.
- Congestive Heart Failure: Initial dosing ranges from 2.5 to 5 mg orally once daily, with titration increased cautiously as tolerated, usually not exceeding 40 mg daily. Careful monitoring during dose escalation is recommended to avoid hypotension due to hypovolemia.
- Acute Myocardial Infarction: Therapy starts within 24 hours of onset with an initial oral dose of 5 mg, followed by 5 mg at 24 hours, then 10 mg at 48 hours. Maintenance dosing is 10 mg once daily continued for at least six weeks to improve survival.
- Pediatric Hypertension: For children aged 6 years and older, starting dose is weight-based at 0.07 mg/kg once daily up to a maximum of 5 mg initially. Dose adjustments may be made based on blood pressure response at 1 to 2 week intervals. Safety and efficacy have not been established for patients under 6 years or with significant renal impairment.

Specific Patient Populations:
- Geriatric patients often start dosing from 2.5 to 5 mg once daily with slow titration increments of 2.5 to 5 mg every 1 to 2 weeks, maintaining maximum doses of 40 mg once daily.
- Renal impairment requires dosage adjustments due to diminished clearance; dosing intervals may be extended or doses reduced according to creatinine clearance measurements.
- Patients on diuretics or with volume depletion require cautious initiation at lower doses such as 2.5 or 5 mg to reduce risk of symptomatic hypotension.
- The medication is typically avoided or used cautiously in pediatric patients below six years or those with glomerular filtration rates less than 30 mL/min.
Overall, the formulation and wide range of tablet strengths enable tailored therapeutic regimens aligned with clinical guidelines and patient-specific factors.

Mechanism Of Action

Lisinopril, the active ingredient in Zestril, exerts its clinical effects primarily through inhibition of angiotensin-converting enzyme (ACE). ACE is a key enzyme in the renin-angiotensin-aldosterone system (RAAS) responsible for converting angiotensin I into the potent vasoconstrictor angiotensin II. By inhibiting this enzyme, lisinopril decreases angiotensin II levels, resulting in vasodilation of both arterioles and veins. This reduces systemic vascular resistance and lowers blood pressure, easing the workload of the heart and improving cardiac efficiency.

Beyond vasodilation, lisinopril decreases aldosterone secretion from the adrenal cortex. Reduced aldosterone leads to diminished sodium and water retention, decreasing blood volume and preload. These combined effects contribute to the beneficial therapeutic outcomes in hypertension and congestive heart failure by reducing both cardiac preload and afterload. Additionally, ACE inhibition prevents degradation of bradykinin, a vasodilator peptide, which may further enhance vasodilation but also accounts for some adverse effects like cough.

At the cellular level, lisinopril modulates endothelial function by promoting nitric oxide availability and inhibiting oxidative stress. This improves vascular compliance and inhibits pathological remodeling seen in heart failure and post-myocardial infarction states. The drug’s impact on preventing maladaptive cardiac hypertrophy and fibrosis has been demonstrated in clinical studies, contributing to long-term cardiovascular protection.

Comparatively, lisinopril’s mechanism is similar to other ACE inhibitors like enalapril and ramipril; however, its pharmacokinetic properties, such as lack of hepatic metabolism and renal excretion unchanged, differentiate it regarding dosing considerations. Clinical trials such as the Consistent Randomized studies in hypertension and SAVE trial post-myocardial infarction have confirmed lisinopril’s effectiveness in reducing mortality, improving heart function, and controlling blood pressure through these molecular pathways.

Pharmacological Actions

Inhibits angiotensin-converting enzyme (ACE), decreasing angiotensin II production
Causes vasodilation of arterial and venous vessels, reducing systemic vascular resistance
Suppresses aldosterone secretion, leading to decreased sodium and water retention
Enhances bradykinin levels contributing to improved endothelial function and vasodilation
Reduces preload and afterload on the heart, easing cardiac workload
Improves cardiac remodeling and prevents progression of heart failure
Lowers blood pressure effectively in both adults and pediatric populations
Exerts renal protective effects by modulating intraglomerular pressure
Does not undergo hepatic metabolism, minimizing metabolic drug interactions
Eliminated unchanged via kidneys, requiring dose adjustments in renal impairment
Improves survival rates post-myocardial infarction by reducing cardiac remodeling
Maintains relatively long half-life enabling once-daily dosing
Enhances nitric oxide bioavailability and reduces oxidative stress at the vascular endothelium
Exhibits low plasma protein binding facilitating effective distribution in extracellular fluid
Does not cross blood-brain barrier significantly, limiting central nervous system side effects

Therapeutic Or Clinical Uses

Management of hypertension in adults and children aged 6 years and older
Treatment of congestive heart failure to improve symptoms and survival
Reduction of mortality and improvement of cardiac function after acute myocardial infarction
Adjunctive therapy to lower blood pressure when combined with diuretics
Used off-label for diabetic nephropathy to reduce proteinuria and preserve kidney function
Improvement of left ventricular dysfunction and cardiac remodeling
Prevention of stroke and other cardiovascular events through blood pressure control
Treatment of patients intolerant to other antihypertensive agents
Renoprotection in patients with hypertension and renal impairment
Used in patients requiring once-daily dosing for enhanced adherence
Management of volume overload states via modulation of RAAS
Reduction of hospitalizations related to heart failure exacerbations
Potential benefit in delaying progression of chronic kidney disease
First-line agent in many hypertension and heart failure clinical guidelines
May be used in combination with other antihypertensives such as diuretics and calcium channel blockers

Side Or Adverse Effects

Persistent dry, nonproductive cough due to bradykinin accumulation
Hypotension, especially after the first dose or in hypovolemic patients
Hyperkalemia resulting from aldosterone suppression and potassium retention
Elevated serum creatinine or renal impairment, particularly in patients with pre-existing kidney disease
Angioedema characterized by swelling of face, lips, tongue, or throat requiring immediate medical attention
Dizziness and headache due to vasodilation and blood pressure lowering effects
Fatigue and malaise common during dose titration
Rash and other allergic skin reactions
Potential leukopenia or neutropenia, with rare risk of agranulocytosis
Rare cases of liver dysfunction and elevated hepatic enzymes
Nausea or gastrointestinal discomfort
Chest pain reported but less commonly associated with the medication
Tachycardia may occur as a compensatory response to hypotension
Possible increases in blood urea nitrogen (BUN)
Electrolyte imbalances including hyponatremia

Precautions

Do not use during pregnancy due to risk of fetal injury or death, particularly in second and third trimesters
Avoid use in patients with a history of angioedema related to ACE inhibitors
Monitor renal function closely in patients with renal impairment or on diuretics
Use cautiously in patients with low blood pressure or volume depletion to prevent symptomatic hypotension
Avoid concurrent use with potassium supplements or potassium-sparing diuretics unless closely monitored
Adjust dosage in geriatric patients starting at lower doses with slow titration
Monitor blood potassium levels periodically to detect hyperkalemia early
Discontinue prior to planned surgery or anesthesia as hypotension may be exacerbated
Avoid use with sacubitril-containing agents due to risk of angioedema; ensure a 36-hour washout period
Exercise caution when prescribing to diabetic patients, particularly with concomitant use of aliskiren
Use careful dose titration in heart failure patients to avoid hypovolemia
Avoid use in pediatric patients under 6 years or with severe renal impairment without specialist advice
Patients should maintain adequate hydration to reduce risk of renal failure
Monitor for signs of neutropenia in patients with collagen vascular disease or immunosuppression
Educate patients about symptoms of angioedema and instruct to seek immediate care if they occur

Warnings

Black box warning regarding fetal toxicity; discontinue as soon as pregnancy is detected
Risk of angioedema which can be life-threatening; prompt discontinuation is required
Potential for first-dose hypotension, especially in volume-depleted individuals
Concomitant use with sacubitril-containing drugs is contraindicated due to angioedema risk
May cause hyperkalemia, especially in patients with renal impairment or taking potassium supplements
Use with caution in patients with bilateral renal artery stenosis or a single functioning kidney
Not recommended in pediatric patients under 6 years or with low glomerular filtration rate (<30 mL/min)
Risk of impaired renal function and acute kidney injury in predisposed patients
May cause hypotension in patients on concurrent diuretic therapy or after significant fluid loss
Discontinue if signs of liver dysfunction or cholestatic jaundice appear
Potential interactions with NSAIDs may reduce antihypertensive effect and impair renal function
Avoid abrupt cessation in patients with heart failure to prevent clinical deterioration
Administer cautiously to patients undergoing surgery or anesthesia due to potential for hypotension
Inform patients about potential dizziness and risk of falls from hypotension
Monitor for symptoms suggestive of neutropenia or infection during therapy

Contraindication

Known hypersensitivity or allergy to lisinopril or any other ACE inhibitors
History of angioedema associated with previous ACE inhibitor therapy
Pregnancy due to risk of fetal toxicity and death during second and third trimesters
Concomitant use with sacubitril-containing products (Entresto) within 36 hours
Use with aliskiren in patients with diabetes or renal impairment
Patients with hereditary or idiopathic angioedema
Severe bilateral renal artery stenosis
Children younger than 6 years of age or with inadequate renal function (<30 mL/min) without specialist supervision
History of angioedema unrelated to ACE inhibitor exposure may also warrant caution or avoidance
Known hypersensitivity to any component of the tablet ingredients

Drug Interactions

Diuretics (especially potassium-sparing) increase risk of hyperkalemia when used with lisinopril
Nonsteroidal anti-inflammatory drugs (NSAIDs) including aspirin, ibuprofen, and naproxen can reduce antihypertensive efficacy and impair renal function
Potassium supplements or salt substitutes can cause dangerous increases in serum potassium
Concomitant use of aliskiren in diabetic patients increases risk of renal impairment and hypotension
Use with sacubitril-containing agents is contraindicated due to angioedema risk
Insulin and other antidiabetic agents may have enhanced blood glucose-lowering effects, requiring dose monitoring
Drugs used for organ transplant rejection prevention (temsirolimus, sirolimus, everolimus) may increase risk of nephrotoxicity
Other antihypertensives can have additive hypotensive effects
Lithium toxicity risk may be increased due to decreased renal clearance
Gold injections combined with ACE inhibitors may increase risk of nitritoid reactions
Concurrent administration with mTOR inhibitors can potentiate adverse renal effects
Cautious use with sympathomimetics as blood pressure effects may be altered
Use with diuretics like hydrochlorothiazide may require dose adjustment for lisinopril
Drug interactions with calcium channel blockers may affect blood pressure control
Combination therapies require monitoring of renal function, electrolytes, and blood pressure regularly

Preparations Of The Drug

Oral tablets available in strengths of 2.5 mg, 5 mg, 10 mg, 20 mg, 30 mg, and 40 mg
Inactive ingredients include calcium phosphate, magnesium stearate, mannitol, starch, red ferric oxide (in 5,10,20,30 mg tablets), and yellow ferric oxide (in 40 mg tablets)
Manufactured by AstraZeneca UK Limited
Tablets are designed for once-daily oral administration
The tablets should be stored tightly closed at room temperature away from moisture and heat
No special food or fluid restrictions needed during administration
Non-prescription forms are not available; prescription required
Also available as Qbrelis, an oral solution formulation at 1 mg/mL, for patients with swallowing difficulties (not under Zestril brand)
Packaging includes blister packs or bottles depending on manufacturer and regional availability
Physical appearance varies by dose with differing colors for ease of identification
No parenteral or injectable forms are available under Zestril brand
Shelf life and storage guidelines must be followed to maintain drug stability
Patients should not freeze the tablets and keep them out of reach of children
Tablets may be split only if the tablet is scored and approved for such use
Preservation of drug potency relies on adherence to recommended storage conditions