What are the sustained release medication options for Atenolol (beta blocker) 50 mg twice daily (bid)?

Sustained Release Beta-Blocker Options for Replacing Atenolol 50 mg BID

Metoprolol succinate extended-release (ER) 100 mg once daily is the most appropriate sustained-release alternative to atenolol 50 mg twice daily. 1, 2, 3

Rationale for Conversion

Atenolol 50 mg twice daily (100 mg total daily dose) can be effectively replaced with a once-daily sustained-release beta-blocker that provides equivalent beta-blockade over 24 hours. When selecting an appropriate alternative:

• Metoprolol succinate ER is specifically designed for once-daily dosing with consistent plasma concentrations throughout the 24-hour period 3
• The usual dosing range for metoprolol succinate is 50-200 mg once daily 2
• Metoprolol succinate 100 mg daily provides comparable beta-blockade to atenolol 100 mg daily 3

Available Sustained-Release Beta-Blocker Options

First-Line Option:

• Metoprolol succinate ER (Toprol XL): 100 mg once daily
  • Provides consistent 24-hour beta-blockade 3
  • Maintains beta-1 selectivity throughout dosing period 3
  • Avoids high peak plasma concentrations that can reduce selectivity 3

Alternative Options:

• Bisoprolol: 10 mg once daily 1

  • Beta-1 selective
  • Long half-life allows for once-daily dosing
  • Preferred in heart failure patients

• Nadolol: 80-120 mg once daily 1

  • Non-cardioselective beta-blocker
  • Long half-life (17-24 hours) allows once-daily dosing
  • Caution in patients with reactive airway disease due to non-selectivity

Dosing Considerations

When converting from atenolol to metoprolol succinate:

• Atenolol 100 mg daily (50 mg BID) ≈ Metoprolol succinate 100 mg once daily
• Start with 100 mg once daily and adjust based on blood pressure response
• Maximum recommended daily dose of metoprolol succinate is 400 mg 2

Special populations:

• Women may require lower doses (approximately 50% less) than men for equivalent effect 2
• Elderly patients may also require lower doses 2
• No dose adjustment needed for renal impairment with metoprolol succinate (unlike atenolol which requires dose adjustment) 4

Monitoring Recommendations

After switching to sustained-release therapy:

• Check blood pressure and heart rate within 2 weeks of transition 2
• Monitor for symptom improvement and side effects
• Ensure adequate 24-hour blood pressure control, particularly in the early morning hours
• Follow up at 12 weeks after final dose titration 2

Clinical Advantages of Sustained-Release Formulations

1. Improved adherence with once-daily dosing
2. More consistent beta-blockade throughout 24 hours
3. Reduced peak plasma concentrations may minimize side effects 3
4. Better maintenance of beta-1 selectivity due to avoidance of high peak plasma levels 3
5. Potentially fewer CNS side effects compared to more lipid-soluble beta-blockers 4

Potential Pitfalls and Cautions

• Avoid abrupt discontinuation of beta-blockers; taper gradually to prevent rebound hypertension 2
• Sustained-release beta-blockers are contraindicated in marked first-degree AV block, second or third-degree AV block without pacemaker, severe bradycardia, hypotension, decompensated heart failure, cardiogenic shock, and severe bronchospastic disease 2
• Beta-blockers should be used with caution in patients with diabetes, as they may mask hypoglycemic symptoms
• Metoprolol is primarily metabolized by the liver, so dose adjustments may be necessary in patients with significant hepatic dysfunction 2