• 목록
• 답변
• 글쓰기
• 게시판 리스트 옵션
  • 수정
  • 삭제

Cozaar, the brand name for losartan potassium, belongs to the class of angiotensin II receptor blockers (ARBs), a cornerstone in the management of hypertension and related cardiovascular and renal disorders. First approved by the U.S. Food and Drug Administration in 1995, Cozaar has become one of the most widely prescribed antihypertensive agents globally due to its efficacy, tolerability, and favorable side-effect profile compared to older drug classes. This report provides a detailed overview of Cozaar, covering its mechanism of action, pharmacokinetics, clinical indications, dosing, adverse effects, drug interactions, and place in current therapeutic guidelines.

Pharmacology and Mechanism of Action

Losartan acts by selectively blocking the binding of angiotensin II to the AT1 receptor subtype, which is predominantly located in vascular smooth muscle, adrenal glands, kidneys, and heart. Angiotensin II, a potent vasoconstrictor produced via the renin‑angiotensin‑aldosterone system (RAAS), normally binds to AT1 receptors to cause vasoconstriction, aldosterone secretion, sodium and water retention, and sympathetic activation. By antagonizing this interaction, losartan dilates blood vessels, reduces peripheral vascular resistance, lowers blood pressure, and decreases aldosterone release. Unlike angiotensin-converting enzyme (ACE) inhibitors, ARBs do not inhibit the degradation of bradykinin, thereby avoiding the troublesome dry cough associated with ACE inhibitors. Losartan also does not block AT2 receptors, which are thought to mediate beneficial effects such as vasodilation and tissue repair.

Pharmacokinetics

After oral administration, losartan is well absorbed but undergoes extensive first-pass metabolism in the liver, primarily by cytochrome P450 2C9 and 3A4, to its active carboxylic acid metabolite, EXP3174. This metabolite is 10 to 40 times more potent than the parent compound and accounts for most of the drug’s antihypertensive effect. Peak plasma concentrations of losartan occur about one hour after dosing, while EXP3174 peaks at three to four hours. The elimination half-life of losartan is approximately two hours, and that of the active metabolite is six to nine hours. Both are highly bound to plasma proteins (98–99%). Losartan and its metabolites are excreted via bile and urine. Dosage adjustment is recommended for patients with hepatic impairment or severe renal dysfunction, and Fiprofort Plus Spot-On: Controle de Ectoparasitas com Eficácia Clínica Comprovada (Fhnoroeste.com) caution is needed in volume-depleted patients to avoid hypotension.

Clinical Indications

1. Hypertension: Cozaar is indicated for the treatment of essential hypertension in adults and children aged six years and older. It can be used alone or in combination with other antihypertensives such as thiazide diuretics (e.g., hydrochlorothiazide) or calcium channel blockers. In landmark trials like the Losartan Intervention for Endpoint Reduction in Hypertension (LIFE) study, losartan demonstrated superior reduction of cardiovascular morbidity and mortality compared with atenolol, particularly in hypertensive patients with left ventricular hypertrophy.
   
   
2. Diabetic Nephropathy: Losartan is approved to slow the progression of kidney disease in patients with type 2 diabetes and proteinuria. The Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) study showed that losartan reduced the risk of doubling of serum creatinine, end-stage renal disease, or death by 16% compared with placebo, independent of blood pressure lowering.
   
   
3. Stroke Prevention in Hypertensive Patients with Left Ventricular Hypertrophy: The LIFE trial also demonstrated a significant reduction in stroke risk with losartan-based therapy compared with atenolol-based therapy.
   
   
4. Heart Failure: While not FDA-approved for heart failure, losartan is sometimes used off-label or as an alternative in patients who cannot tolerate ACE inhibitors. It is also a component of the fixed-dose combination product containing losartan and hydrochlorothiazide (Hyzaar) for improved blood pressure control.
   
   

The usual starting dose for hypertension in adults is 50 mg once daily, titrated to 100 mg once daily if needed. For diabetic nephropathy, the recommended dose is 50 mg once daily initially, titrated to 100 mg once daily based on blood pressure response. In children six years or older, dosing is weight-based. The drug can be taken without regard to meals. It is important to correct volume or sodium depletion before initiation to minimize the risk of symptomatic hypotension.

Adverse Effects

Cozaar is generally well tolerated. The most common side effects are dizziness, nasopharyngitis, upper respiratory infection, fatigue, and back pain. Notably, the incidence of cough is significantly lower than with ACE inhibitors (about 3.1% for losartan vs. 8.8% for lisinopril in comparative trials). Angioedema, a serious but rare allergic reaction, can occur with ARBs although less frequently than with ACE inhibitors. Hyperkalemia may develop, especially in patients with chronic kidney disease, diabetes, or those taking potassium-sparing diuretics or potassium supplements. Orthostatic hypotension, particularly in the elderly or volume-depleted patients, is possible. Hypoglycemia has been reported in diabetic patients receiving insulin or sulfonylureas due to enhanced insulin sensitivity. Other rare effects include hepatotoxicity, pancreatitis, and renal impairment. Because losartan inhibits the RAAS, it can cause fetal renal damage and oligohydramnios when used during pregnancy, making it contraindicated in the second and third trimesters. Women of childbearing potential should use effective contraception.

Drug Interactions

Losartan can interact with nonsteroidal anti-inflammatory drugs (NSAIDs), which may diminish its antihypertensive effect and increase the risk of acute kidney injury and hyperkalemia. Co-administration with potassium-sparing diuretics, potassium supplements, or trimethoprim can further raise serum potassium. Rifampin and fluconazole (CYP2C9 inhibitors) may affect losartan metabolism, but clinical significance is limited. Combining losartan with other RAAS blockers (e.g., ACE inhibitors, aliskiren) is generally avoided due to increased risk of hypotension, hyperkalemia, and renal impairment.

Therapeutic Guidelines and Place in Therapy

Current guidelines from the American College of Cardiology/American Heart Association (ACC/AHA) and the European Society of Cardiology (ESC) recommend ARBs including losartan as first-line therapy for hypertension, especially in patients with compelling indications such as diabetic nephropathy, left ventricular hypertrophy, heart failure with reduced ejection fraction (where ACE inhibitors remain first-line, but ARBs are an alternative), or prior myocardial infarction. Losartan is also favored in patients who have experienced ACE-inhibitor-induced cough or angioedema. For hypertension management, monotherapy with an ARB may be sufficient for stage 1 hypertension, but combination therapy is often required to achieve target blood pressure (usually <130/80 mmHg). The LIFE trial data give losartan a unique advantage for hypertensive patients with left ventricular hypertrophy.

Conclusion

Cozaar (losartan) remains an essential component of modern cardiovascular pharmacotherapy. Its selective blockade of the AT1 receptor provides effective blood pressure reduction, renoprotection in diabetic kidney disease, and stroke prevention, all with a low incidence of adverse effects, particularly cough. Ongoing research continues to explore potential benefits in heart failure, atrial fibrillation, and vascular aging. As with all RAAS inhibitors, proper patient selection, monitoring of renal function and electrolytes, and avoidance during pregnancy are crucial. When prescribed judiciously, losartan offers a well-tolerated and evidence-based option for millions of patients worldwide with hypertension and its related complications.