DESCRIPTION
PHARMACOLOGY-
Angiotensin II the principal pressor agent of the rennin-angiotensin system, is responsible for effects such as vasoconstriction, stimulation of synthesis and release of aldosterone, cardiac stimulation, and renal reabsorption of sodium. Irbesartan is a specific competitive antagonist of AT1 receptors with a much greater affinity (more than 8500-fold) for the AT1 receptor than for the AT2 receptor and no agonist activity. Irbesartan's inhibition of angiotensin II binding to the AT1 receptor leads to multiple effects including vasodilatation, a reduction in the secretion of vasopressin, and reduction in the production and secretion of aldosterone. The resulting effect is a decrease in blood pressure.
MECHANISM OF ACTION-
Irbesartan is a nonpeptide tetrazole derivative and an angiotensin II antagonist that selectively blocks the binding of angiotensin II to the AT1 receptor. In the renin-angiotensin system, angiotensin I is converted by angiotensin-converting enzyme 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 AT1 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).
SIDE EFFECTS-
Diarrhea,heartburn, excessive tiredness, swelling of the face, throat, tongue,lips, eyes, hands, feet, ankles, or lower legs, hoarseness,difficulty breathing or swallowing.
DRUG DRUG INTERACTION-
1. The serum concentration of Irbesartan can be increased when it is combined with Abiraterone.
2. Irbesartan may increase the hypotensive activities of Acebutolol.
3. The risk or severity of adverse effects can be increased when Irbesartan is combined with Aceclofenac.
4. The metabolism of Acenocoumarol can be decreased when combined with Irbesartan.
5 .The metabolism of Acetaminophen can be decreased when combined with Irbesartan.
6. The risk or severity of adverse effects can be increased when Acetazolamide is combined with Irbesartan.
7. The risk or severity of adverse effects can be increased when Irbesartan is combined with Acetylsalicylic acid.
8. The risk or severity of adverse effects can be increased when Irbesartan is combined with Adapalene.
USES-
Irbesartan is used to treat high blood pressure (hypertension) and to help protect the kidneys from damage due to diabetes. Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. Irbesartan belongs to a class of drugs called angiotensin receptor blockers (ARBs). It works by relaxing blood vessels so that blood can flow more easily.
This drug may also be used to treat heart failure.
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