Is propranolol (beta blocker) cardioselective?

Propranolol is NOT Cardioselective

Propranolol is a nonselective beta-adrenergic blocker that blocks both beta-1 receptors (in the heart) and beta-2 receptors (in the lungs and blood vessels), making it fundamentally different from cardioselective agents like metoprolol, atenolol, or bisoprolol. 1

Pharmacologic Classification

• Propranolol competitively blocks both beta-1 and beta-2 adrenergic receptors without selectivity 1
• Beta-1 receptors are located primarily in the myocardium and control heart rate, contractility, and AV node conduction 2
• Beta-2 receptors are located in vascular and bronchial smooth muscle; their blockade causes vasoconstriction and bronchoconstriction 2
• This nonselective blockade distinguishes propranolol from cardioselective agents like metoprolol (beta-1 selective) 2

Clinical Implications of Nonselective Blockade

The lack of cardioselectivity has important clinical consequences:

• Respiratory effects: Propranolol causes more bronchoconstriction than cardioselective agents and should be avoided in patients with asthma or obstructive airway disease 2
• Peripheral vascular effects: Beta-2 blockade leads to peripheral vasoconstriction, which can worsen symptoms in patients with peripheral vascular disease 3
• Metabolic effects: Nonselective beta blockade may cause more hypoglycemia and mask hypoglycemic symptoms compared to cardioselective agents 4

Comparison with Cardioselective Agents

The ACC/AHA guidelines explicitly distinguish propranolol from cardioselective beta blockers:

• Cardioselective agents (beta-1 selective): metoprolol, atenolol, bisoprolol, esmolol, betaxolol 2
• Nonselective agents: propranolol, nadolol, timolol 2
• When patients have reactive airway disease or COPD, guidelines recommend using "low doses of a beta-1–selective agent" rather than nonselective agents like propranolol 2

Practical Prescribing Guidance

When beta-2 blockade is problematic:

• In patients with mild wheezing or COPD, use a cardioselective agent like metoprolol at reduced doses (e.g., 12.5 mg) rather than propranolol 2
• Cardioselective beta blockers do not produce clinically significant adverse respiratory effects in most COPD patients, whereas nonselective agents like propranolol carry higher risk 2
• For hypertension management, cardioselective agents (metoprolol, bisoprolol) are preferred over nonselective agents like propranolol 2

When nonselective blockade may be acceptable:

• Propranolol has been studied and used effectively in acute coronary syndromes, though cardioselective agents are generally preferred 2
• In patients without contraindications (no asthma, no severe COPD, no peripheral vascular disease), propranolol remains an effective option 4