Adults

Initial dose is usually 50 mg once daily. May be increased to 100 mg once daily if needed.

Elderly

No initial dosage adjustment is typically needed for most elderly patients. Consider starting with 25 mg once daily if volume depletion is suspected.

Renal_impairment

No initial dosage adjustment required for mild to moderate renal impairment. For severe renal impairment or dialysis, a lower starting dose (e.g., 25 mg once daily) may be considered.

Onset

Antihypertensive effect begins within 6 hours, maximal effect within 3-6 weeks.

Excretion

Approximately 35% excreted in urine and 60% in feces, primarily as unchanged drug and active metabolite.

Half life

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

Absorption

Rapidly absorbed from the gastrointestinal tract; bioavailability is approximately 33%.

Metabolism

Undergoes extensive first-pass metabolism by cytochrome P450 enzymes (CYP2C9 and CYP3A4) to an active carboxylic acid metabolite (E-3174) and inactive metabolites.

NSAIDs

May reduce antihypertensive effect and increase risk of renal impairment.

Lithium

May increase serum lithium levels and toxicity.

Aliskiren

Contraindicated in diabetic or renal impaired patients due to increased risk of adverse events.

Potassium-sparing diuretics

May increase risk of hyperkalemia.