Pharmacology: Pharmacodynamics: Losartan potassium is an angiotensin II receptor (type AT1) antagonist with antihypertensive activity due mainly to selective blockade of AT1 receptors and the consequent reduced pressor effect of angiotensin II.
Pharmacokinetics: Losartan potassium is readily absorbed from gastrointestinal tract after oral doses, but undergoes substantial first pass metabolism. It is metabolized primarily by cytochrome P450 isoenzyme CYP2C9 and CYP3A4 to an active metabolite, which has greater pharmacological activity than losartan potassium. Losartan potassium and its metabolite are more than 98% bound to plasma proteins. Although food may decrease the absorption rate of losartan potassium and peak concentration achievement, the therapeutic effect is not altered. Losartan potassium is excreted in the urine, and in the faeces via bile, as unchanged drug and metabolites.