Angiotensin receptor blockers · Cardiovascular
Losartan
Cozaar®(brand names vary by market)
The first ARB: RAAS blockade without the bradykinin baggage.
Mechanism
Selective AT1 receptor antagonist: blocks angiotensin II at its receptor, so cough and angioedema rates sit near placebo.
Open the interactive pathwayIndications
- Hypertension
- Proteinuric diabetic kidney disease
- Heart failure when ACE inhibitors are not tolerated
Formulations
Dosing concepts
Switching
The usual landing spot after ACE-inhibitor cough; the same creatinine and potassium rules apply.
Concepts, not prescribing instructions. Practice numbers live in current references and local protocols.
Pharmacokinetics
- Bioavailability
- ~33%
- Half-life
- 2 h (parent), 6-9 h (active metabolite)
- Elimination
- hepatic: CYP2C9/3A4 to an active carboxylic-acid metabolite that does most of the work
Adverse effects
- Hyperkalemiacommon & serious
- Hypotension, dizzinesscommon
- Renal function decline in the wrong hemodynamicsserious
Contraindications & precautions
Contraindications
- Pregnancy
- Bilateral renal artery stenosis
Precautions
- Volume depletion
- Combination with ACE inhibitors (no extra benefit, more harm)
Interactions
- ACE inhibitors / ARBs + Potassium-sparing diuretics, K supplements, salt substitutescautionAdditive hyperkalemia, worst with renal impairment layered on top.
- ACE inhibitor / ARB + diuretic + NSAID (the 'triple whammy')avoidAcute kidney injury, classically in a dehydrated older adult who bought ibuprofen for a sore knee.
Monitoring
Creatinine and potassium
Same physiology as ACE inhibitors · Baseline and 1-2 weeks after changes
Blood pressure
Titration endpoint
Counselling points
- Same pregnancy avoidance and salt-substitute cautions as ACE inhibitors.
- Dizziness on standing usually settles; rise slowly.
Clinical pearls
- Do not combine ACE inhibitor + ARB for hypertension: trials showed more hyperkalemia and AKI without outcome benefit.
References & review
- Losartan product monograph (consult the current version for your market) (monograph)
- Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed. (reference-work)
Last reviewed 2026-08-15 · jurisdiction: global · drug information changes; verify against current references before practice use.