Can atenolol (beta-blocker) be administered twice daily?

Can Atenolol Be Given Twice Per Day?

Yes, atenolol can be administered twice daily, though once-daily dosing is generally preferred and equally effective for most indications. 1

FDA-Approved Dosing Regimens

The FDA label explicitly supports both once-daily and twice-daily atenolol administration depending on the clinical indication 1:

• Hypertension: 50-100 mg once daily is standard, with doses beyond 100 mg daily unlikely to produce additional benefit 1
• Angina pectoris: 50-200 mg once daily, though some patients may require 200 mg once daily for optimal 24-hour control 1
• Acute myocardial infarction: After IV loading, 50 mg twice daily or 100 mg once daily for 6-9 days 1

Evidence Supporting Once-Daily vs. Twice-Daily Dosing

The pharmacokinetic profile of atenolol strongly favors once-daily administration for most patients. Multiple high-quality studies demonstrate therapeutic equivalence:

• A controlled trial in hypertensive patients found no significant difference in blood pressure control between once-daily and twice-daily administration of the same total dose 2
• Continuous 24-hour blood pressure monitoring confirmed that 100 mg atenolol once daily maintains significant antihypertensive effect throughout the entire 24-hour period 3
• Comparative studies show atenolol provides more sustained 24-hour blood pressure and heart rate control than metoprolol when both are given once daily, due to atenolol's longer half-life 4

When Twice-Daily Dosing May Be Appropriate

Twice-daily dosing should be considered in specific clinical scenarios 1:

• Acute myocardial infarction: The FDA label recommends 50 mg twice daily (or 100 mg once daily) following IV loading for post-MI management 1
• Perioperative settings: Studies used atenolol 5-10 mg IV followed by twice-daily oral dosing for 3 days postoperatively 5
• Dose titration in angina: When initiating therapy, some clinicians may prefer divided dosing before transitioning to once-daily administration 1

Pharmacokinetic Rationale

The long elimination half-life of atenolol (16-27 hours in patients with normal renal function) supports once-daily dosing 1, 6:

• Peak plasma concentrations occur 3 hours after oral administration, with measurable levels persisting for 24 hours 6
• No accumulation or tolerance develops with repeated once-daily administration over 2 weeks 6
• Pharmacodynamic effects (blood pressure reduction, heart rate control) remain stable throughout the 24-hour dosing interval 6

Critical Dosing Considerations

Renal impairment significantly affects atenolol dosing frequency and total daily dose 1:

• Creatinine clearance 15-35 mL/min/1.73m²: Maximum 50 mg daily (once daily only) 1
• Creatinine clearance <15 mL/min/1.73m²: Maximum 25 mg daily (once daily only) 1
• Hemodialysis patients: 25-50 mg after each dialysis under hospital supervision 1

Guideline Recommendations Across Indications

ACC/AHA guidelines consistently reference atenolol as a once-daily agent 5:

• Unstable angina/NSTEMI: 50-200 mg per day (single daily dose) 5
• Hypertension: 25-100 mg twice daily OR 50-200 mg once daily, with once-daily preferred 5
• Perioperative beta-blockade: Various regimens studied, including twice-daily dosing for short-term perioperative use 5

Common Pitfalls to Avoid

• Do not assume twice-daily dosing improves efficacy: Increasing dosage beyond 100 mg daily (whether once or twice daily) rarely provides additional antihypertensive benefit 1
• Do not split doses in renal impairment: Patients with significant renal dysfunction should receive reduced total daily doses given once daily, not divided 1
• Do not abruptly discontinue: Whether on once or twice-daily dosing, gradual tapering is essential to prevent rebound hypertension and angina exacerbation 1

Practical Clinical Algorithm

For new atenolol prescriptions:

1. Start with once-daily dosing (50-100 mg) for hypertension or chronic angina 1
2. Consider twice-daily dosing only for acute MI management (50 mg BID) or if specifically indicated by clinical trial protocols 1
3. Assess renal function before prescribing—adjust to once-daily reduced dosing if CrCl <35 mL/min 1
4. Monitor blood pressure and heart rate at trough (just before next dose) to confirm 24-hour coverage 1

For patients already on twice-daily dosing:

• Consolidation to once-daily dosing is reasonable and supported by evidence, using the same total daily dose 2, 3
• This may improve adherence without compromising efficacy 2