Propranolol Dose Equivalent to Metoprolol 12.5 mg Every 12 Hours
For a patient taking metoprolol 12.5 mg via G-tube every 12 hours (total 25 mg daily), the equivalent propranolol dose is 40 mg twice daily (80 mg total daily), starting the morning after the last metoprolol dose without overlap or tapering. 1
Conversion Rationale and Initial Dosing
The American College of Cardiology, American Heart Association, and European Society of Cardiology recommend switching from metoprolol 25 mg daily to propranolol 80-120 mg daily in divided doses. 1
Start with propranolol 40 mg twice daily as the initial conversion dose, with the option to increase to 60 mg twice daily if additional symptom control is needed after 3-5 days. 1
Propranolol must be administered in divided doses (typically twice or three times daily) due to its shorter half-life compared to metoprolol, making it unsuitable for once-daily dosing. 1
Administration via G-Tube
Propranolol immediate-release tablets can be crushed and administered via G-tube, though the FDA label does not specifically address G-tube administration. 2
Administer propranolol with or after meals to enhance absorption and reduce the risk of hypoglycemia. 1
Do not use propranolol extended-release capsules via G-tube, as crushing destroys the sustained-release mechanism. 2
Critical Pre-Conversion Safety Checks
Before switching, verify the absence of: 1
- Decompensated heart failure
- Second or third-degree heart block without a functioning pacemaker
- Active asthma or severe reactive airway disease
- Systolic blood pressure ≤100 mmHg
- Heart rate ≤50 bpm
Monitoring Protocol After Conversion
Check blood pressure and heart rate 2-4 hours after the first propranolol dose to assess for excessive beta-blockade or inadequate symptom control. 1
Monitor for symptomatic bradycardia (heart rate <60 bpm with dizziness or lightheadedness). 1
Assess for hypotension (systolic blood pressure <100 mmHg with symptoms like dizziness or lightheadedness). 1
Continue monitoring blood pressure and heart rate at each visit during the first 2-4 weeks after conversion. 1
Propranolol-Specific Considerations for Anxiety
Propranolol is a non-selective beta-blocker with greater CNS penetration than metoprolol, which may provide superior anxiety symptom control but also increases the risk of sleep disturbances or vivid dreams. 1
For anxiety disorders, therapeutic doses typically range from 80-320 mg daily in divided doses, with some patients requiring up to 1200 mg daily for severe symptoms. 3
The somatic symptoms of anxiety (palpitations, tremor, tachycardia) respond particularly well to propranolol, with both somatic and psychic symptoms showing improvement in most patients. 3, 4
Propranolol has greater potential for bronchospasm in patients with reactive airway disease compared to the more cardioselective metoprolol. 1
Common Pitfalls to Avoid
Never attempt a direct mg-for-mg conversion between metoprolol and propranolol, as they have different pharmacokinetics and potencies. 1
Do not use propranolol extended-release formulations via G-tube, as they cannot be crushed without destroying the sustained-release mechanism. 2
Avoid propranolol in patients with asthma or severe COPD, as its non-selective beta-blockade significantly increases bronchospasm risk compared to cardioselective metoprolol. 1
Monitor for depression, as propranolol may induce or worsen depressive symptoms in predisposed patients, though this effect is controversial. 5, 6
Dose Titration for Anxiety Management
If 40 mg twice daily provides inadequate anxiety control after 3-5 days, increase to 60 mg twice daily. 1
Further titration may proceed in 40-80 mg daily increments every 3-7 days until optimal symptom control is achieved, up to a maximum of 320 mg daily for most patients. 2, 3
The usual effective dose range for anxiety is 80-320 mg daily in divided doses, though some patients with severe symptoms may require higher doses. 3