Lisinopril (Teva)

Active Ingredient & Mechanism of Action

• Active Ingredient: Lisinopril dihydrate.
• Mechanism: Lisinopril inhibits the enzyme responsible for converting angiotensin I to angiotensin II, a potent vasoconstrictor that also triggers aldosterone secretion:
  1. Blood Pressure Reduction: By reducing circulating levels of angiotensin II, it promotes systemic arterial relaxation, decreases peripheral vascular resistance, and lowers blood pressure.
  2. Reduced Aldosterone Secretion: Lower aldosterone levels lead to decreased sodium and water retention, helping reduce circulating fluid volume.
  3. Cardioprotection & Preload/Afterload Reduction: By dilating blood vessels and lowering fluid resistance, lisinopril reduces both cardiac preload and afterload, easing the workload on a failing or damaged heart.

Available Strengths & Dosage Forms

• Lisinopril 2.5 mg Tablets: Typically used as a low starting dose for heart failure, post-myocardial infarction, or patients at risk of severe hypotension.
• Lisinopril 5 mg Tablets: Standard initial dose for hypertension in adults, or maintenance dose for heart failure.
• Lisinopril 10 mg & 20 mg Tablets: Common target maintenance doses for essential hypertension and clinical post-MI regimens.
• Lisinopril 40 mg Tablets: Maximum recommended daily dosage for blood pressure control.

Clinical Indications

• Hypertension: Used as monotherapy or in combination with other classes of antihypertensive agents (such as thiazide diuretics) to lower systemic blood pressure and minimize stroke and heart attack risks.
• Heart Failure: Adjunctive therapy alongside diuretics and digitalis to improve survival and reduce hospitalizations in patients with symptomatic heart failure.
• Acute Myocardial Infarction (AMI): Reduction of mortality when initiated within 24 hours of an acute heart attack in hemodynamically stable patients.
• Diabetic Nephropathy: Slows the progression of renal disease and microalbuminuria in hypertensive patients with type 1 diabetes mellitus.

Key Pharmacokinetics

• Absorption: Rapidly absorbed following oral administration with peak serum concentrations reached in approximately 6 to 8 hours. Absorption is unaffected by food.
• No Hepatic Activation Required: Lisinopril is not a prodrug; it exerts active enzymatic inhibition directly without requiring hepatic metabolism.
• Half-Life & Elimination: Features an effective elimination half-life of approximately 12 hours, allowing for once-daily dosing. It does not bind to plasma proteins and is excreted entirely unchanged in the urine.

Administration & Dosage

• Usage: Administered orally once daily, with or without food, at approximately the same time each day.
• Renal Adjustments: Because it is eliminated unchanged by the kidneys, initial dosages must be adjusted downward in patients with impaired renal function ($\text{GFR} < 30\text{ mL/min}$).

Safety Profile & Considerations

• Common Side Effects: Dizziness, headache, fatigue, persistent dry cough (due to bradykinin accumulation), and hyperkalemia (elevated potassium levels).
• Boxed Warning (Fetal Toxicity): Drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus. Discontinue immediately if pregnancy is detected.
• Contraindications: Known history of angioedema related to previous ACE inhibitor treatment, hereditary/idiopathic angioedema, and concomitant use with aliskiren in diabetic patients.
• Key Interactions:
  • Potassium Supplements / Potassium-Sparing Diuretics: Increased risk of hyperkalemia.
  • NSAIDs: May reduce antihypertensive effect and increase the risk of renal impairment.
  • Lithium: May increase serum lithium concentrations and toxicity.

Note: Lisinopril (Teva) is a prescription-only drug. Initiating treatment, monitoring kidney function, and adjusting dosage should strictly follow the directions of a licensed healthcare professional.