Pharmacology: Irbesartan is an angiotensin receptor antagonist.
Angiotensin II acts as a vasoconstrictor. In addition to causing direct vasoconstriction, angiotensin II also stimulates the release of aldosterone. Once aldosterone is released, sodium as well as water are reabsorbed. The end result is an elevation in blood pressure.
Irbesartan binds to AT1 angiotensin II receptor. This binding prevents angiotensin II from binding to the receptor thereby blocking the vasoconstriction and the aldosterone-secreting effects of angiotensin II.
Pharmacokinetics: Onset of action: Peak effect: 1-2 hrs. Duration: >24 hrs.
Distribution: Vd: 53-93 L. Protein binding, plasma: 90%.
Metabolism: Hepatic, primarily CYP2C9.
Half-life: 11-15 hrs.
Time to Peak, Serum: 1.5-2 hrs.
Excretion: Feces (80%), urine (20%).