Is it safe to prescribe losartan (angiotensin II receptor antagonist) 50 mg twice daily (bid) to a patient, particularly an older adult or one with a history of impaired renal function (kidney disease)?

Can You Give Losartan 50 mg BID?

Yes, losartan 50 mg twice daily (total 100 mg/day) is an acceptable and guideline-supported dosing regimen for hypertension and heart failure, though once-daily dosing of the full 100 mg dose is more commonly recommended. 1

Guideline-Supported Dosing Frequency

The 2017 ACC/AHA Hypertension Guidelines explicitly list losartan's usual dose range as 50-100 mg/day with a daily frequency of "1 or 2," meaning both once-daily and twice-daily administration are acceptable. 1 This provides clear evidence that splitting the total daily dose is within standard practice parameters.

Clinical Rationale for Dosing Strategy

For most patients, once-daily dosing of 100 mg is preferred because:

• Losartan's active metabolite E-3174 has a half-life of 6-9 hours, providing extended duration of action 2
• Once-daily dosing improves medication adherence 2
• Clinical trials demonstrating cardiovascular benefits primarily used once-daily dosing 3

However, twice-daily dosing (50 mg BID) may be appropriate when:

• More consistent 24-hour blood pressure coverage is desired 3
• The patient experiences end-of-dose blood pressure elevation on once-daily dosing 1
• Titrating from lower doses in volume-depleted or elderly patients 4

Maximum Dose Considerations

The total daily dose should not exceed 100 mg for hypertension. 1, 4 For heart failure with reduced ejection fraction, higher doses up to 150 mg daily have been studied and may provide additional benefit, though this exceeds typical hypertension dosing. 3

Critical Safety Monitoring

When prescribing losartan at any dose, monitor the following within 1-2 weeks of initiation or dose changes:

• Serum potassium: Risk of hyperkalemia, especially with CKD, diabetes, or concomitant potassium-sparing agents 1, 4
• Serum creatinine/eGFR: Risk of acute renal failure in patients with bilateral renal artery stenosis, volume depletion, or severe heart failure 4, 5
• Blood pressure: Risk of symptomatic hypotension in volume- or salt-depleted patients 4

Absolute Contraindications to Consider

Never combine losartan with:

• ACE inhibitors or direct renin inhibitors (aliskiren): This combination increases risks of hyperkalemia, syncope, and acute kidney injury without additional benefit 1, 4
• Pregnancy: Discontinue immediately if pregnancy is detected due to fetal toxicity 4

Special Population Adjustments

• Hepatic impairment: Start at 25 mg once daily in mild-to-moderate hepatic dysfunction 4
• Renal impairment: No dose adjustment needed unless patient is also volume-depleted 4
• Elderly patients: No dose adjustment required; losartan is well-tolerated in this population 4, 6

Practical Implementation

If prescribing 50 mg BID specifically:

• Ensure the total daily dose (100 mg) is appropriate for the indication 1
• Consider whether once-daily 100 mg dosing would provide equivalent benefit with better adherence 2
• If blood pressure remains uncontrolled, add hydrochlorothiazide 12.5-25 mg daily rather than exceeding 100 mg losartan for hypertension 1, 3