Angiotensin II (medication)

Overview

Angiotensin II is a medication used primarily in the management of hypotension (low blood pressure) in adults with septic shock or other forms of vasodilatory shock. It is a synthetic form of the naturally occurring hormone angiotensin II, which plays a critical role in the renin-angiotensin system (RAS), a hormone system that regulates blood pressure and fluid balance.

Mechanism of Action

Diagram of the angiotensin II molecule

Angiotensin II acts as a potent vasoconstrictor, meaning it narrows blood vessels, thereby increasing blood pressure. It binds to angiotensin II receptors, primarily the AT1 receptor, which leads to a cascade of events resulting in increased vascular resistance and aldosterone secretion. Aldosterone promotes sodium and water retention, further contributing to increased blood volume and pressure.

Clinical Use

Angiotensin II is administered intravenously in a hospital setting. It is indicated for patients with septic or other forms of vasodilatory shock who do not respond adequately to conventional therapies such as norepinephrine or vasopressin. The goal of treatment is to restore adequate blood pressure and ensure sufficient perfusion of vital organs.

Side Effects

The use of angiotensin II can lead to several side effects, including:

• Hypertension (excessively high blood pressure)
• Thrombosis (formation of blood clots)
• Tachycardia (increased heart rate)
• Peripheral ischemia (reduced blood flow to the limbs)

Contraindications

Angiotensin II should be used with caution in patients with a history of thromboembolic events, as it may increase the risk of clot formation. It is also contraindicated in patients with known hypersensitivity to the drug.

Pharmacokinetics

Angiotensin II has a rapid onset of action, typically within minutes of administration. Its effects are short-lived, necessitating continuous infusion to maintain therapeutic blood pressure levels. The drug is metabolized by aminopeptidases in the blood and tissues.

Related pages

• Renin-angiotensin system
• Vasodilatory shock
• Septic shock
• Vasopressor