Medication Name and Class

Lisinopril, an angiotensin-converting enzyme (ACE) inhibitor, is used to treat hypertension, heart failure, and to improve survival after a heart attack. This medication works by relaxing blood vessels, lowering blood pressure, and reducing strain on the heart.

Pharmacological Properties

Lisinopril is absorbed from the gastrointestinal tract with a bioavailability of approximately 25%. It reaches peak plasma concentrations within 7 hours after oral administration. It is primarily excreted unchanged in the urine, with an elimination half-life of about 12 hours. It functions by inhibiting the conversion of angiotensin I to angiotensin II, leading to decreased vasoconstriction and aldosterone secretion.

Dosage Forms and Strengths

Lisinopril is available in oral tablet form with strengths of 2.5 mg, 5 mg, 10 mg, 20 mg, 30 mg, and 40 mg. It is also manufactured in an oral solution form for certain clinical scenarios, with a concentration of 1 mg/mL.

Standard Adult Dosage

For hypertension, the initial dose is typically 10 mg once daily, which may be adjusted according to the patient’s response, up to a maximum of 40 mg daily. For heart failure, the recommended starting dose is generally 2.5-5 mg once daily, with adjustments made based on clinical response. Post-myocardial infarction treatment usually starts with 5 mg followed by increasing doses, contingent on tolerance and clinical evaluation.

Mechanism of Action

Lisinopril inhibits angiotensin-converting enzyme (ACE), which decreases the conversion of angiotensin I to the vasoconstrictor angiotensin II. This leads to vasodilation, decreased secretion of aldosterone, reduced reabsorption of sodium and water, and ultimately lowered blood pressure. Additionally, it reduces remodeling after myocardial infarction by mitigating pathological cardiac changes.

Indications for Use

Lisinopril is indicated for the treatment of hypertension, heart failure, and for improving survival after a myocardial infarction. It may also be used in specific types of chronic kidney disease for blood pressure control.

Contraindications

Lisinopril is contraindicated in patients with a history of angioedema related to previous treatment with an ACE inhibitor, in patients with hereditary angioedema, and in those hypersensitive to any component of the drug. It is also contraindicated in patients with anuria and during pregnancy.

Potential Drug Interactions

Lisinopril may interact with diuretics, other antihypertensive agents, potassium supplements, and potassium-sparing diuretics. It can enhance the blood pressure-lowering effect of these medications. When combined with NSAIDs, the antihypertensive effect may be diminished, and the risk of renal impairment may increase. Caution is advised when used with lithium, as it can lead to increased lithium levels and toxicity. Alcohol may enhance the hypotensive effect of lisinopril.

Side Effects Overview

Common side effects include dizziness, hypotension, hyperkalemia, and renal impairment. More serious but less frequent adverse reactions include angioedema, liver dysfunction, and neutropenia. Patients may also experience a persistent dry cough. Monitoring kidney function and electrolytes is important during treatment.

Monitoring Parameters

Patients on lisinopril should be regularly monitored for blood pressure, kidney function (serum creatinine), and electrolyte levels, particularly potassium. It is also important to monitor for signs of angioedema, especially during the initial stages of therapy and following dose increases. Liver function tests should be performed in patients with indicative symptoms.

Administration Instructions

Lisinopril should be taken orally once a day, with or without food. Tablets should be swallowed whole with a glass of water. The medication should be taken at the same time each day to maintain consistent blood levels. If a dose is missed, it should be taken as soon as remembered unless it is close to the time for the next dose; in such cases, the missed dose should be skipped.

Clinical Pharmacokinetics

Lisinopril has an oral bioavailability of approximately 25%. Food does not significantly affect its absorption. Once absorbed, it is not significantly metabolized and is excreted unchanged in the urine. In patients with renal impairment, the drug’s half-life is prolonged, necessitating dose adjustment based on glomerular filtration rate (GFR) values.

Specific Population Considerations

In elderly patients, there may be an increased risk of side effects, necessitating careful monitoring and dose adjustments. Pediatric use is limited and should be based on weight and clinical need. In patients with renal impairment, initial dosing should be conservative, and titration should be based on therapeutic response and tolerability. Caution should be exercised when prescribing to pregnant women due to potential teratogenic effects.

Laboratory Test Interactions

Lisinopril may cause false elevations in blood urea nitrogen (BUN) and creatinine, especially during the initial treatment phase. Care should be taken to differentiate between drug-induced increases and genuine renal dysfunction. Monitoring serum potassium and other electrolytes is crucial to avoiding hyperkalemia or electrolyte imbalances.