Co-Ivyzar Mechanism of Action

Pharmacology: Irbesartan is a specific competitive antagonist of angiotensin I (AT1) receptors with a much greater affinity (>8500-fold) for the AT1 receptor than for the AT2 receptor and no agonist activity. It is a potent antihypertensive drug which is administered orally, and may be given alone or in combination with diuretics and/or other antihypertensive agents.
Hydrochlorothiazide is a moderately potent diuretic and exert this effect by reducing the reabsorption of electrolytes from the renal tubules, thereby increasing the excretion of sodium and chloride ions, and consequently water.
Pharmacokinetics: Irbesartan is an orally active agent that does not require biotransformation into an active form. It is rapidly absorbed from the gastrointestinal tract with an oral bioavailability of 60-80%. Peak plasma concentrations of irbesartan occur 1.5-2 hrs after an oral dose. Irbesartan is about 96% bound to plasma proteins. It undergoes some metabolism in the liver, primarily by the cytochrome P-450 isoenzyme CYP2C9, to inactive metabolites. It is excreted as unchanged drug and metabolites in the bile and in urine. The terminal elimination t_½ is about 11-15 hrs.
Hydrochlorothiazide is fairly rapidly absorbed from the gastrointestinal tract with an oral bioavailability of 65-70%. It has been estimated to have a plasma t_½ of between 5 and 15 hrs and appears to be preferentially bound to red blood cells. It is excreted mainly unchanged in the urine.