Angiotensin-II formed from angiotensin-I in a reaction catalyzed by angiotensin-converting enzyme (ACE), is a potent vasoconstrictor, the primary vasoactive hormone of the renin-angiotensin system and an important component in the pathophysiology of hypertension. It also stimulates aldosterone secretion by the adrenal cortex. Olmesartan blocks the vasoconstrictor and aldosterone-secreting effects of angiotensin-II by selectively blocking the binding of angiotensin-II to the AT 1 receptor found in many tissues (e.g. vascular smooth muscle, adrenal gland). In-vitro-binding studies indicate that Olmesartan is a reversible & competitive inhibitor of AT 1 receptor. Olmesartan does not inhibit ACE (kinase-I, the enzyme that converts angiotensin-I to angiotensin-II and degrades bradykinin).

Olmesartan Medoxomil is indicated for the treatment of hypertension. It may be used alone or in combination with other antihypertensive agents.

Dosage must be individualized. The usual recommended starting dose of Olmesartan is 20 mg once daily when used as monotherapy in patients who are not volume-contracted. For patients requiring further reduction in blood pressure after 2 weeks of therapy, the dose of Olmesartan may be increased to 40 mg. Doses above 40 mg do not appear to have a greater effect. Twice-daily dosing offers no advantage over the same total dose given once daily.

No initial dosage adjustment is recommended for elderly patients, for patients with moderate to marked renal impairment (creatinine clearance <40 ml/min) or with moderate to marked hepatic dysfunction. For patients with possible depletion of intravascular volume (e.g. patients treated with diuretics, particularly those with impaired renal function), Olmesartan should be initiated under close medical supervision and consideration should be given to use of a lower starting dose. Olmesartan may be administered with or without food.

Olmesartan is contraindicated in patients who are hypersensitive to any component of this product.

Common: The most common side effects include Back pain, bronchitis, creatine phosphokinase increased, diarrhea, headache, hematuria, hyperglycemia, hypertriglyceridemia, influenza-like symptoms, pharyngitis, rhinitis, and sinusitis.

Rare: Chest pain, peripheral edema, arthritis.

Overdose Effects

Symptoms: There is no experience of overdose with Olmesartan. The most likely effects of olmesartan medoxomil overdosage are hypotension and tachycardia; bradycardia could be encountered if parasympathetic (vagal) stimulation occurred.

As a consequence of inhibiting the renin-angiotensin-aldosterone system, changes in renal function may be anticipated in susceptible individuals treated with olmesartan medoxomil. In patients whose renal function may depend upon the activity of the renin-angiotensin-aldosterone system (e.g. patients with severe congestive heart failure), treatment with angiotensin-converting enzyme inhibitors and angiotensin receptor antagonists has been associated with oliguria and/or progressive azotemia and (rarely) with acute renal failure and/or death. Similar results may be anticipated in patients treated with olmesartan medoxomil.

Use in Special Populations

Paediatric use: Safety and effectiveness in paediatric patients have not been established.