What selective β‑1 adrenergic blocker is used for hypertension or angina, what is its usual adult dosing, and what are appropriate alternative β‑1 blockers?

Selective β-1 Adrenergic Blockers for Hypertension and Angina

Metoprolol and atenolol are the primary selective β-1 adrenergic blockers used for hypertension and angina, with metoprolol dosed at 50-200 mg twice daily and atenolol at 50-200 mg once daily. 1, 2

Primary β-1 Selective Agents

The ACC/AHA guidelines identify several β-1 selective (cardioselective) blockers studied in cardiovascular disease, with metoprolol, atenolol, and bisoprolol being the most commonly used 1:

• Metoprolol: 50-200 mg twice daily for angina; no intrinsic sympathomimetic activity 1
• Atenolol: 50-200 mg once daily for both hypertension and angina 1, 2
• Bisoprolol: 10 mg once daily 1
• Betaxolol: 10-20 mg once daily 1
• Acebutolol: 200-600 mg twice daily (has partial agonist activity, which is less preferred) 1
• Esmolol: 50-300 mcg/kg/min IV (short-acting, used for acute situations) 1

Dosing Specifics

Atenolol Dosing (from FDA Label)

For hypertension: Start with 50 mg once daily, increase to 100 mg once daily if needed after 1-2 weeks; doses beyond 100 mg unlikely to provide additional benefit 2

For angina: Start with 50 mg once daily, increase to 100 mg once daily after one week if needed; some patients require 200 mg once daily for optimal 24-hour control 2

Metoprolol Dosing

For acute coronary syndromes: IV metoprolol 5 mg over 1-2 minutes, repeated every 5 minutes for total of 15 mg, then oral 25-50 mg every 6 hours for 48 hours, followed by maintenance of up to 100 mg twice daily 1

For chronic angina/hypertension: 50-200 mg twice daily 1

Selection Algorithm

Choose metoprolol or esmolol when:

• Patient has reactive airway disease or COPD (use low doses initially, e.g., 12.5 mg metoprolol orally) 1
• Concerns exist about drug tolerance (short-acting β-1 specific agents preferred) 1
• Acute situation requiring IV administration with ability to titrate quickly 1

Choose atenolol when:

• Once-daily dosing compliance is a concern 2, 3
• Patient has renal impairment requiring dose adjustment (atenolol is renally eliminated and requires dose reduction when GFR <30 mL/min) 2, 4
• Minimizing CNS side effects is important (atenolol has low lipid solubility and limited brain penetration) 4, 3

Choose bisoprolol when:

• Once-daily dosing is desired with high β-1 selectivity 1, 5

Critical Contraindications

Absolute contraindications 1:

• Marked first-degree AV block (PR interval >0.24 seconds)
• Second- or third-degree AV block without functioning pacemaker
• Severe LV dysfunction or acute heart failure (rales, S3 gallop)
• Significant bradycardia (heart rate <50 bpm)
• Hypotension (systolic BP <90 mmHg)
• History of asthma (relative contraindication; use cautiously with low-dose β-1 selective agent if necessary)

High-risk features for cardiogenic shock (avoid IV beta-blockers) 1:

• Tachycardia with Killip Class II or III
• Evidence of low-output state (oliguria)
• Hemodynamic instability

Important Clinical Nuances

Beta-blockers without intrinsic sympathomimetic activity are strongly preferred for cardiovascular indications 1. This means acebutolol is less desirable despite being β-1 selective 1.

Atenolol's cardiovascular benefit in hypertension has been questioned in recent analyses, though it remains guideline-recommended 1. The evidence is more robust for metoprolol in acute coronary syndromes 1.

Route of administration matters: ACC/AHA guidelines recommend oral initiation within 24 hours for stable patients, reserving IV administration for ongoing rest pain with tachycardia or hypertension 1. Early aggressive IV beta-blockade increases shock risk 1.

Renal dosing is critical for atenolol: Dose must be reduced when GFR <30 mL/min due to exclusive renal elimination 2, 4. Metoprolol does not require renal dose adjustment 4.