Hartzar Mechanism of Action

Pharmacology: Pharmacokinetics: Losartan Potassium is an angiotensin II receptor antagonist with antihypertensive activity due mainly to selective blockade of ATP's receptors and the consequent reduced pressure effect of angiotensin II.
Losartan Potassium is readily absorbed from the gastrointestinal tract following oral administration, with an oral bioavailability of about 33%. It undergoes first pass metabolism to form an active carboxylic acid metabolites E-3174 (EXP-3174), which has greater pharmacological activity than losartan, and some inactive metabolites. Metabolism is primarily by cytochrome P450 isoenzymes CYP2C9 and CYP3A4. Peak plasma concentrations of losartan and E-3174 occur about 1 hour and 3 to 4 hours, respectively, after an oral dose. Both losartan and E-3174 are more than 98% bound to plasma proteins. Losartan is excreted in the urine and in the feces via bile, as unchanged drug and metabolites. Following oral dosing, about 35% of the dose is excreted in the urine and about 60% in the feces. The terminal elimination half-lives of losartan and E-3174 are about 1.5 hours to 2.5 hours and 3 to 9 hours respectively.