Description

Losartan Potassium is a medication classified as an angiotensin II receptor blocker (ARB). It is a potent and selective antihypertensive drug that works by blocking the effects of the hormone angiotensin II. The “potassium” in its name refers to the salt form used to improve the drug’s stability and bioavailability for oral administration.

Indications

Losartan is primarily used for the treatment of various cardiovascular and renal conditions. Its main indications include:

Hypertension (High Blood Pressure): It is a first-line agent used to lower blood pressure, either alone or in combination with other antihypertensive drugs.

• Diabetic Nephropathy: It is indicated to slow the progression of kidney disease in patients with Type 2 diabetes who also have hypertension.
• Stroke Risk Reduction: It is prescribed to reduce the risk of stroke in patients with high blood pressure and an enlarged heart (left ventricular hypertrophy).

Mechanism of Action

Losartan’s therapeutic effects are a result of its ability to block the renin-angiotensin-aldosterone system (RAAS), a hormonal system that plays a key role in regulating blood pressure. Here’s a step-by-step breakdown of how it works:

1. Blockade of Angiotensin II Receptors: Losartan acts as a competitive antagonist at the angiotensin II type 1 (AT1) receptors. It binds to these receptors, preventing the powerful hormone angiotensin II from attaching to them.
2. Prevention of Vasoconstriction: Angiotensin II is a potent vasoconstrictor, meaning it causes blood vessels to narrow. By blocking its receptors, losartan prevents this narrowing, leading to vasodilation (the widening of blood vessels). This decreases the peripheral resistance, making it easier for the heart to pump blood
3. Reduced Aldosterone Release: The binding of angiotensin II to its receptors also stimulates the release of aldosterone, a hormone that causes the body to retain sodium and water. By blocking this action, losartan helps to decrease the body’s fluid volume, which further lowers blood pressure.

4. Overall Effect: The combined effect of vasodilation and reduced fluid retention leads to a significant and sustained reduction in blood pressure, easing the workload on the heart and helping to protect blood vessels and vital organs like the kidneys.

Unlike ACE inhibitors (another class of blood pressure medications), losartan does not interfere with the breakdown of bradykinin, which is why it is associated with a lower risk of causing the side effect of a dry cough.