When should you stop taking losartan (angiotensin II receptor blocker) 100mg/hydrochlorothiazide (diuretic) 12.5mg in a patient?

When to Stop Losartan 100mg/Hydrochlorothiazide 12.5mg

Losartan/hydrochlorothiazide should be discontinued immediately upon pregnancy detection, and strongly considered for discontinuation in patients with gout (switching to alternative antihypertensives), while monitoring for and stopping if acute renal failure, hyperkalemia, or symptomatic hypotension develops. 1

Mandatory Discontinuation Scenarios

Pregnancy

• Stop immediately when pregnancy is detected - drugs acting on the renin-angiotensin system cause fetal toxicity during second and third trimesters, including fetal renal dysfunction, oligohydramnios, fetal lung hypoplasia, skeletal deformations, skull hypoplasia, anuria, hypotension, renal failure, and death 1

Acute Renal Failure

• Discontinue if clinically significant decrease in renal function occurs - patients with renal artery stenosis, chronic kidney disease, severe heart failure, or volume depletion are at particular risk 1
• Monitor renal function periodically, especially in angiotensin-dependent patients 1
• Both losartan and ACE inhibitors carry equal risk of renal dysfunction (10.5% incidence in elderly heart failure patients), with no evidence that losartan is better tolerated 2

Severe Hyperkalemia

• Stop or reduce dose if hyperkalemia develops despite appropriate treatment 1
• Monitor serum potassium periodically, particularly with concomitant potassium-sparing agents or in patients with renal impairment 1

Symptomatic Hypotension

• Discontinue if symptomatic hypotension occurs in volume- or salt-depleted patients 1
• Correct volume/salt depletion before restarting if clinically appropriate 1

Strong Consideration for Discontinuation

Gout Patients

• Switch hydrochlorothiazide to alternative antihypertensive when feasible - the 2020 American College of Rheumatology conditionally recommends this for all gout patients regardless of disease activity 3
• Losartan can be continued or preferentially chosen as it has modest uricosuric properties, increasing urinary uric acid excretion by ~25% and reducing serum uric acid by 20-47 μmol/L 4
• The hydrochlorothiazide component increases gout risk, while losartan may actually help lower uric acid levels 4
• Consider switching to losartan monotherapy (if BP control permits) or losartan plus calcium channel blocker combination 4

Clinical Monitoring for Potential Discontinuation

Bilateral Renal Artery Stenosis

• Avoid or stop in bilateral renal artery stenosis or unilateral stenosis in solitary kidney - these patients have angiotensin-dependent renal function 2
• Case reports demonstrate reversible renal deterioration upon discontinuation 2

Severe Congestive Heart Failure with Renal Dependence

• Exercise caution and monitor closely - renal function may depend on renin-angiotensin system activity 1
• Consider discontinuation if renal function deteriorates 1

Drug Intolerance

• Stop if persistent cough develops - though less common with losartan than ACE inhibitors, switch to calcium channel blocker or other alternative if this occurs 3
• Discontinue if other intolerable side effects emerge that don't resolve with dose adjustment 3

When NOT to Stop

Age ≥80 Years

• Do not interrupt successful, well-tolerated therapy simply because patient reaches 80 years of age 3
• Continue if blood pressure control is achieved and medication is tolerated 3

Hyponatremia

• Stop the hydrochlorothiazide component but losartan can be continued - switch to loop diuretic if diuretic still needed 3

Appropriate Cardiovascular Indications

• Continue if needed for blood pressure control, especially in diabetic patients where goal BP is <130/80 mmHg 3
• The combination provides additive antihypertensive effects with 78-87% of patients achieving BP control 5, 6

Common Pitfalls to Avoid

• Do not assume losartan protects against renal dysfunction - it carries the same renal risks as ACE inhibitors despite different mechanism 2
• Do not continue hydrochlorothiazide in gout patients when alternatives exist - this is a modifiable risk factor 3, 4
• Do not forget to check standing blood pressure in elderly patients to assess for postural hypotension before discontinuing 3
• Do not stop abruptly without alternative antihypertensive plan in patients requiring blood pressure control - arrange transition to alternative therapy 3