Losartan is an angiotensin II receptor blocker (ARB) that selectively binds to the AT1 receptor, preventing vasoconstriction and aldosterone secretion. It is the first ARB approved for clinical use.
Also known as: Cozaar
ARB + NSAID: reduced antihypertensive effect and renal risk.
NSAIDs inhibit renal prostaglandins, reducing ARB efficacy and increasing the risk of renal dysfunction and hyperkalaemia.
DailyMed/FDA (NIH/NLM) — approved Losartan label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1dadbe02-289c-4312-9e65-40f3314dcc31
ARB + spironolactone: serious risk of hyperkalaemia.
Both reduce renal potassium excretion. The combination can cause severe hyperkalaemia. Monitor K+ and renal function.
DailyMed/FDA (NIH/NLM) — approved Losartan label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1dadbe02-289c-4312-9e65-40f3314dcc31
Losartan (ARB) reduces potassium excretion — adding potassium-rich foods (salt substitutes, bananas, juices) raises hyperkalaemia risk.
Do not use salt substitutes; moderate potassium-rich fruits/juices; keep blood tests up to date.
Site monograph (losartan — hyperkalaemia risk with potassium sparing); EMC-UK losartan SmPC 4.4.
Dose adjustment required in moderate-severe hepatic impairment.
Start with reduced dose in hepatic impairment.
DailyMed/FDA (NIH/NLM) — approved Losartan label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1dadbe02-289c-4312-9e65-40f3314dcc31
Losartan is contraindicated in previous ARB-associated angioedema or hereditary angioedema.
Do not use in patients with a history of angioedema.
EMC-UK (MHRA) — approved Losartan SmPC: https://www.medicines.org.uk/emc/product/7783/smpc
Losartan is contraindicated in bilateral renal artery stenosis (or stenosis in a single functioning kidney) because of the risk of acute renal failure.
Do not use; assess renal function before starting an ARB.
EMC-UK (MHRA) — approved Losartan SmPC: https://www.medicines.org.uk/emc/product/7783/smpc
CONTRAINDICATED in pregnancy. Risk of fetal/neonatal renal injury.
CONTRAINDICATED in all trimesters.
Unknown if excreted in breast milk. Prefer alternatives.
Discontinue before conception. Do not use during pregnancy or breastfeeding.
DailyMed/FDA (NIH/NLM) — approved Losartan label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1dadbe02-289c-4312-9e65-40f3314dcc31
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Selective blocker of the angiotensin II AT1 receptor, preventing vasoconstriction, aldosterone secretion, and cardiac remodelling.
Binds to the angiotensin II AT1 receptor with high affinity, blocking all physiological effects of angiotensin II mediated by this receptor.
Oral bioavailability: ~33%. Food does not significantly affect absorption. Tmax: 1-2 hours (losartan); 3-4 hours (E-3174).
Metabolised by CYP2C9 and CYP3A4 to the active metabolite E-3174 (10-40x more potent). Induced by rifampicin. Boosted by cimetidine.
2 hours (losartan); 6-9 hours (E-3174). Elimination: ~35% faeces, ~60% urine (metabolites).
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
