losartan potassium: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
losartan potassium: clinical details
Prescribing considerations
- Assess volume depletion, hypotension, renal function, electrolyte disturbance and concomitant medicines before initiation.
- Use caution with renal artery stenosis, renal impairment, heart failure, significant aortic or mitral stenosis, obstructive hypertrophic cardiomyopathy or previous angioedema.
- Losartan exposure is increased in hepatic impairment; severe hepatic impairment is contraindicated.
- Renin–angiotensin system blockers may produce a smaller average blood-pressure response in Black patients with hypertension.
- Review treatment promptly during acute illness associated with dehydration or possible renal compromise.
Contraindications and cautions
- Hypersensitivity to losartan or a product excipient.
- Second or third trimester of pregnancy.
- Severe hepatic impairment.
- Aliskiren co-administration in diabetes mellitus or renal impairment with GFR below 60 mL/min/1.73 m².
Monitoring
- Before treatment: blood pressure, estimated GFR or serum creatinine, potassium and sodium.
- Recheck blood pressure, renal function and electrolytes after initiation or treatment changes, with earlier or more frequent review in higher-risk patients.
- Continue periodic renal function, sodium and potassium monitoring once stable and repeat testing during acute illness or possible renal compromise.
- Investigate clinically important rises in potassium or creatinine and review dehydration, renal artery disease and interacting medicines.
Clinical pharmacology
Losartan is an oral selective AT1-receptor antagonist. It undergoes first-pass metabolism, mainly through CYP2C9, to a more potent active carboxylic-acid metabolite. Losartan and its active metabolite are highly protein bound; neither is removed by haemodialysis.
Formulation and product differences
- The selected products are lactose-containing film-coated tablets.
- The selected 25 mg tablet is white to off-white, oval and marked “J” and “25”.
- The selected 50 mg tablet is white to off-white, oval, scored on one side and marked “J” and “50”; check the specific product information before splitting.
- Special-order losartan liquids may be available for swallowing difficulties; crushing film-coated tablets is off-label.
losartan potassium preparations and strengths
Tablet
Route: Oral
Strengths: 12.5 mg, 25 mg, 50 mg, 100 mg
losartan potassium interactions
Tell the prescriber or pharmacist about all medicines, supplements and salt substitutes. Important examples include:
Potassium supplements, potassium-containing salt substitutes, potassium-sparing diuretics, trimethoprim or heparin
These can increase blood potassium; combined use may require avoidance or closer blood-test monitoring.
NSAIDs, including ibuprofen and anti-inflammatory doses of aspirin
They may reduce the blood-pressure effect and increase the risk of kidney impairment and high potassium, particularly with dehydration or existing kidney disease.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.