Angiotensin II receptor blocker

Angiotensin II receptor blockers

Angiotensin II receptor blockers (ARBs) lower blood pressure by blocking the vasoconstrictive effects of angiotensin II. Specific drugs include:

• candesartan cilexetil
• eprosartan
• irbesartan
• losartan
• olmesartan
• telmisartan
• valsartan.

Warning!

Adverse reactions to ARBs

Adverse reactions to angiotensin II receptor blockers (ARBs) include:

• headache and fatigue
• cough and tickling in the throat
• angioedema
• GI reactions
• increased serum potassium level
• transient elevations of blood urea nitrogen and serum creatinine levels.

Pharmacokinetics

ARBs have varying pharmacokinetic properties and all are highly bound to plasma proteins.

 

 

Pharmacodynamics

ARBs act by interfering with the renin-angiotensin-aldosterone system. Specifically, these drugs block the binding of angiotensin II to the AT₁ receptor. This prevents angiotensin II from exerting its vasoconstricting properties and from promoting the excretion of aldosterone. Both of these actions result in lowered blood pressure.

 

ARBs don’t inhibit the conversion of angiotensin I to angiotensin II, nor do they cause a breakdown in bradykinin (a vasodilator).

 

 

Pharmacotherapeutics

ARBs may be used alone or in combination with other drugs such as a diuretic. Valsartan may also be used as an alternative to an ACE inhibitor or for the management of heart failure. Because irbesartan and losartan protect the renal system, they’re often prescribed for patients with type 2 diabetes. Losartan is also used to reduce the risk of stroke in high-risk patients with hypertension and left ventricular hypertrophy. 

 

 

Drug interactions

ARBs can interact with other drugs in various ways.

• When losartan is taken with fluconazole, an increased blood level of losartan may result, leading to hypotension.
• NSAIDs reduce the antihypertensive effects of ARBs.
• Rifampin may increase metabolism of losartan and decrease its antihypertensive effect.
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• Candesartan may increase blood levels of lithium, leading to lithium toxicity.
• When digoxin is taken with telmisartan, an increased blood level of digoxin may occur, possibly leading to digoxin toxicity.
• Potassium supplements may increase the risk of hyperkalemia when used with ARBs.