From the Guidelines
To convert from atenolol 25 mg to metoprolol, the equivalent dose would be metoprolol 50 mg daily, as metoprolol has approximately half the potency of atenolol, requiring a 1:2 ratio for equivalent beta-blocking effects 1. When switching between these beta-blockers, metoprolol can be started immediately after the last dose of atenolol.
- Metoprolol is typically given twice daily (25 mg twice daily) due to its shorter half-life, while atenolol is usually given once daily.
- Both medications are beta-1 selective blockers used for similar conditions like hypertension, angina, and post-myocardial infarction.
- The conversion is necessary because metoprolol has approximately half the potency of atenolol, requiring a 1:2 ratio for equivalent beta-blocking effects.
- Patients should be monitored for blood pressure and heart rate after switching to ensure the new medication is providing adequate control.
- Side effects are similar between the two medications, though metoprolol is more lipophilic and may have slightly different central nervous system effects.
- If the patient was on atenolol for a specific indication like post-heart attack or angina, ensure the metoprolol dosing is appropriate for that particular indication, as guided by the 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction 1 and the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1.
From the Research
Atenolol to Metoprolol Conversion
- The conversion from atenolol to metoprolol is a common practice in the management of hypertension and other cardiovascular diseases 2, 3.
- A study published in the Journal of Clinical Pharmacology compared the safety and efficacy of atenolol and metoprolol in patients with essential hypertension, and found no significant differences in office systolic and diastolic blood pressure between the two treatments 2.
- However, the study did find a slight increase in pulse rate for patients treated with metoprolol, and an increase in morning diastolic blood pressure for those randomized to metoprolol 2.
Dosage and Administration
- The dosage of metoprolol required to achieve equivalent beta-blocking effects as atenolol is not well established, but a general guideline is to start with a lower dose of metoprolol (e.g. 25-50 mg) and titrate upwards as needed 4.
- Metoprolol can be administered once daily, and the succinate formulation is commonly used for the treatment of heart failure and atrial fibrillation 5.
Clinical Considerations
- When switching from atenolol to metoprolol, it is essential to consider the patient's individual clinical status, including the presence of any comorbidities or concomitant medications 4.
- Metoprolol has been shown to be effective in reducing mortality and morbidity in patients with heart failure, and may also be beneficial in the prevention of atherosclerosis and cardiovascular disease 5, 6.
- However, the use of metoprolol in certain patient populations, such as those with asthma or diabetes, requires careful consideration due to its potential effects on respiratory function and glucose metabolism 3, 6.