Why Propranolol (Inderal) is Preferred Over Metoprolol for Anxiety
Propranolol is superior to metoprolol for anxiety because it is a non-selective beta blocker that blocks both beta-1 and beta-2 receptors throughout the body, including peripheral sites where physical anxiety symptoms originate, whereas metoprolol's cardioselective beta-1 blockade primarily targets cardiac tissue and provides less effective control of somatic anxiety manifestations. 1
Pharmacological Basis for Propranolol's Superiority
Non-Selective vs. Cardioselective Blockade
Propranolol blocks both beta-1 and beta-2 receptors, providing comprehensive blockade of peripheral adrenergic symptoms that characterize anxiety, including tremor, palpitations, and sweating 1
Metoprolol is cardioselective, primarily blocking beta-1 receptors in cardiac tissue, which makes it less effective at addressing the peripheral somatic manifestations of anxiety 2
The general principle is that non-selective beta blockers are indicated for anxiety and other psychiatric disorders, while cardioselective agents like metoprolol are reserved for cardiovascular indications 1
Clinical Evidence Supporting Propranolol
Propranolol is the most widely studied and clearly established beta blocker for anxiety disorders, with consistent evidence supporting its efficacy in treating somatic anxiety symptoms 1, 3, 4
Studies demonstrate that propranolol is particularly effective in patients with predominantly somatic anxiety (bodily symptoms like palpitations, tremor, sweating) rather than purely psychic anxiety 5
Propranolol is specifically useful for performance anxiety and social phobias, such as fear of public speaking, typically at doses of 20-40 mg once to three times daily 3
Specific Clinical Indications
Panic Disorder and Generalized Anxiety
For panic disorder, beta blockers are commonly prescribed for symptom relief in combination with cognitive behavioral therapy and/or SSRIs and/or benzodiazepines 1
Propranolol provides symptomatic relief for residual somatic complaints (palpitations, tachycardia) when combined with the patient's ongoing drug regimen 6
The evidence does not support routine use of beta blockers as monotherapy for generalized anxiety disorder or panic disorder, but they serve as useful adjuncts 6, 7
Performance Anxiety
Propranolol is particularly effective for situational performance anxiety, where physical symptoms (tremor, tachycardia) interfere with performance 3
Typical dosing is 20-40 mg taken 30-60 minutes before the anxiety-provoking event 3
Why Metoprolol is Not Preferred
Limited Peripheral Effects
Metoprolol's cardioselectivity means it primarily affects heart rate and blood pressure but has minimal impact on peripheral beta-2 receptors responsible for tremor and other somatic anxiety symptoms 2
While metoprolol has limited evidence of moderate effect in migraine prevention 1, it lacks the established efficacy profile of propranolol for anxiety disorders 1
Guideline Recommendations
Beta blockers are not recommended as first-line agents unless the patient has ischemic heart disease or heart failure 1, 8
When a beta blocker is needed for anxiety, propranolol is the preferred agent based on decades of clinical experience and research 1
Important Clinical Considerations
Contraindications and Cautions
Both propranolol and metoprolol are contraindicated in cardiogenic shock, marked sinus bradycardia, second or third-degree heart block without a pacemaker, and decompensated heart failure 2
Beta blockers may induce depression and should be used cautiously in patients with concurrent depressive illness 6
Never combine propranolol and metoprolol due to risk of additive beta-blockade effects leading to significant bradycardia, heart block, and hypotension 2
Optimal Patient Selection
Reserve propranolol for patients with anxiety characterized by prominent somatic symptoms related to increased adrenergic tone 3, 5
Propranolol is most effective in anxiety disorders of moderate intensity, recent onset, and those seen in general practice settings 3
Consider propranolol when benzodiazepines are contraindicated or have failed to adequately control physical symptoms 7, 4
Dosing and Duration
Typical therapeutic doses range from 20-40 mg, once to three times daily for chronic anxiety 3
Clinical efficacy beyond 4 weeks of continuous use remains to be fully demonstrated 3
Never abruptly discontinue propranolol after regular use, as this can cause rebound symptoms or hypertensive crisis 8
Alternative First-Line Approaches
For generalized anxiety disorder and panic disorder, SSRIs/SNRIs should be considered first-line pharmacotherapy rather than beta blockers 8
If initial psychological treatment is ineffective and a drug is necessary, consider a beta blocker (propranolol) or an antidepressant as first choice in preference to a benzodiazepine for chronic anxiety 4