Adults

Typical starting dose is 50 mg once daily. Max dose 100 mg once daily.

Elderly

No initial dosage adjustment is typically required, but monitoring for hypotension is advised.

Renal_impairment

No initial dosage adjustment needed for mild to moderate impairment. Lower starting dose (e.g., 25 mg) may be considered for severe impairment or patients on dialysis.

Onset

6 hours (initial effect), full effect in 3-6 weeks.

Excretion

Primarily excreted in feces (60%) and urine (35%) as unchanged drug and metabolites.

Half life

Losartan: 2 hours; active metabolite (E-3174): 6-9 hours.

Absorption

Rapidly absorbed from the GI tract; bioavailability is about 33%. Peak plasma concentration within 1 hour for losartan, 3-4 hours for active metabolite.

Metabolism

Undergoes extensive first-pass metabolism by CYP2C9 and CYP3A4 to an active carboxylic acid metabolite (E-3174) and several inactive metabolites.

NSAIDs (e.g., Ibuprofen)

May reduce the antihypertensive effect and increase the risk of renal impairment.

Diuretics (e.g., Furosemide)

May enhance hypotensive effect, leading to excessive blood pressure drop.

Potassium-sparing diuretics (e.g., Spironolactone) or potassium supplements

Increased risk of hyperkalemia.