IRBEGENCopy

• DRUGBANK - Irbesartan
• indication:

  For the treatment of hypertension, as well as diabetic nephropathy with an elevated serum creatinine and proteinuria (>300 mg/day) in patients with type 2 diabetes and hypertension. Irbesartan is also used as a second line agent in the treatment of congestive heart failure.

• pharmacology:

• mechanism:

  Irbesartan is a nonpeptide tetrazole derivative and an angiotensin II antagonist that selectively blocks the binding of angiotensin II to the AT<sub>1</sub> receptor. In the renin-angiotensin system, angiotensin I is converted by angiotensin-converting enzyme (ACE) to form angiotensin II. Angiotensin II stimulates the adrenal cortex to synthesize and secrete aldosterone, which decreases the excretion of sodium and increases the excretion of potassium. Angiotensin II also acts as a vasoconstrictor in vascular smooth muscle. Irbesartan, by blocking the binding of angiotensin II to the AT<sub>1</sub> receptor, promotes vasodilation and decreases the effects of aldosterone. The negative feedback regulation of angiotensin II on renin secretion is also inhibited, but the resulting rise in plasma renin concentrations and consequent rise in angiotensin II plasma concentrations do not counteract the blood pressure–lowering effect that occurs. The action of ARBs is different from ACE inhibitors, which block the conversion of angiotensin I to angiotensin II, meaning that the production of angiotensin II is not completely inhibited, as the hormone can be formed via other enzymes. Also, unlike ACE inhibitors, irbesartan and other ARBs do not interfere with response to bradykinins and substance P, which allows for the absence of adverse effects that are present in ACE inhibitors (eg. dry cough).

• toxicity:

  Hypotension and tachycardia; bradycardia might also occur from overdose, LD<sub>50</sub>=mg/kg(orally in rat)

• absorprion:

  Rapid and complete with an average absolute bioavailability of 60-80%. Food has no affect on bioavailability.

• halflife:

  11-15 hours

• roouteelimination:

  Irbesartan is metabolized via glucuronide conjugation and oxidation. Irbesartan and its metabolites are excreted by both biliary and renal routes. Irbesartan is excreted in the milk of lactating rats.

• volumedistribution:

  * 53 to 93 L

• clearance:

  * 157-176 mL/min