Generic Name : Olmesartan.

Trade Name     : Erastapex.

Drug Class       : Angiotensin II receptors blockers (ARBs).

Forms of The Drug

  • Tablet: 5mg, 20mg, 40mg.

Mechanism of Action

The mechanism of action of Olmesartan involves its interaction with specific receptors and subsequent effects on blood vessels and other physiological processes. Here’s a breakdown of the mechanism of action of Olmesartan:

  1. RAAS and Angiotensin II: The renin-angiotensin-aldosterone system (RAAS) plays a significant role in regulating blood pressure. One of the key components of this system is angiotensin II, a potent vasoconstrictor. Angiotensin II binds to angiotensin II receptors on blood vessels, leading to their constriction (narrowing), which increases blood pressure.
  2. Angiotensin II Receptors: Angiotensin II receptors are of two main types: AT1 and AT2. The AT1 receptor is responsible for the vasoconstrictive effects of angiotensin II, while the AT2 receptor has vasodilatory and other effects that counterbalance the actions of AT1.
  3. Blockade of AT1 Receptors: Olmesartan specifically targets and blocks the AT1 receptors for angiotensin II. It does this by binding to these receptors, preventing the binding of angiotensin II itself.

This blockade leads to several effects:

  1. Vasodilation: By blocking the AT1 receptors, Olmesartan reduces the vasoconstrictive effects of angiotensin II. This leads to relaxation and dilation of blood vessels, which results in decreased resistance to blood flow and subsequently lowers blood pressure.
  2. Aldosterone Secretion: Angiotensin II also stimulates the release of aldosterone, a hormone that promotes sodium and water retention in the kidneys. By inhibiting AT1 receptors, Olmesartan reduces the production of aldosterone, which helps in decreasing the blood volume and further contributes to lowering blood pressure.
  3. Reduced Sodium Reabsorption: Olmesartan’s effects on the kidneys lead to decreased sodium reabsorption. This contributes to the reduction of blood volume and, consequently, blood pressure.
  4. Remodeling of Blood Vessels: Prolonged activation of AT1 receptors can lead to vascular remodeling, a process involving thickening and stiffening of blood vessels. By blocking these receptors, Olmesartan helps prevent or reverse this remodeling process.


  1. Hypertension (High Blood Pressure).
  2. Heart Failure.
  3. Diabetic Nephropathy.
  4. Microalbuminuria in Diabetes.
  5. Renovascular Hypertension.


  1. Hypersensitivity.
  2. Pregnancy.
  3. Severe Renal Impairment.
  4. Biliary Obstruction.
  5. Hereditary Angioedema.
  6. Combination with Aliskiren in Diabetes.

Side Effects

  1. Dizziness.
  2. Headache.
  3. Fatigue.
  4. Diarrhea.
  5. Hyperglycemia.
  6. Hypertriglyceridemia.
  7. Back pain.
  8. Bronchitis.
  9. Inflicted injury.
  10. Flulike symptoms.
  11. Pharyngitis.
  12. Rhinitis.
  13. Sinusitis.
  14. Upper respiratory tract infection (URTI).

Drug Interaction

Other drugs that can interact with it.

  1. Potassium-sparing diuretics (e.g., spironolactone) or potassium supplements.
  2. NSAIDs like ibuprofen and naproxen.
  3. Lithium.
  4. Aliskiren.
  5. Dual Blockade of the Renin-Angiotensin System.
  6. Certain Antacids: Antacids containing aluminum and magnesium hydroxide.
  7. Grapefruit Juice.


  1. Pregnancy:  Category D.
  2. Lactation: Limited information is available regarding the excretion of Olmesartan into human breast milk. However, because of the potential for adverse effects on nursing infants and the lack of comprehensive studies, caution is generally advised when considering the use of Olmesartan during lactation.
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