Can metoprolol be given in patients with asthma?

Metoprolol Use in Asthma Patients

Metoprolol should be avoided in patients with active asthma as it is considered a contraindication, but may be cautiously used in select cases with careful monitoring when cardiovascular benefits outweigh respiratory risks. 1

Pharmacological Considerations

• Metoprolol is a beta-1 selective (cardioselective) adrenergic receptor blocker, but this selectivity is not absolute and at higher plasma concentrations, it also inhibits beta-2 receptors in bronchial musculature 2
• While metoprolol has greater beta-1 selectivity compared to non-selective beta blockers like propranolol, it still demonstrates significant beta-2 blocking activity that can trigger bronchospasm in asthmatic patients 3
• In asthmatic patients, metoprolol reduces FEV1 and FVC, though less significantly than non-selective beta blockers at equivalent beta-1 blocking doses 2

Clinical Evidence in Asthma

• Studies show that even relatively low doses of metoprolol can cause significant bronchoconstriction in asthmatic patients, with some patients requiring withdrawal from treatment due to severe respiratory symptoms 4
• The average maximum tolerated cumulative doses in sensitive asthmatic patients were found to be only 26.8 mg of metoprolol, which is much lower than doses typically required for therapeutic cardiac effects 4
• When metoprolol is administered to asthmatic patients receiving beta-2 agonists (like terbutaline), the bronchodilator plasma concentration needs to be increased two- to four-fold to obtain the same effect on FEV1 3

Guidelines for Use

• The American College of Cardiology guidelines list active asthma as an absolute contraindication for metoprolol 1
• For patients with mild asthma who require beta-blocker therapy, the following precautions should be taken:
  • Use the lowest effective dose of metoprolol (not exceeding 100 mg daily) 5
  • Ensure optimal concurrent bronchodilator treatment with a selective beta-2 agonist 5
  • Monitor respiratory function closely, particularly when initiating therapy 6
  • Consider starting with a very low dose (e.g., 12.5 mg) to assess tolerability 6

Alternative Approaches

• In patients with asthma who need treatment for conditions typically managed with beta blockers:
  • Consider non-dihydropyridine calcium channel blockers (e.g., verapamil or diltiazem) as alternative therapy for conditions like angina or hypertension in asthmatic patients 6
  • For patients with non-ST elevation acute coronary syndromes and contraindications to beta blockers, calcium channel blockers are recommended as initial therapy 6

Clinical Monitoring

• If metoprolol must be used in a patient with a history of asthma:
  • Monitor for wheezing, decreased peak flow, or other signs of bronchospasm 6
  • Be prepared to discontinue the medication if respiratory symptoms worsen 4
  • Recognize that respiratory response to metoprolol cannot be reliably predicted in individual asthmatic patients 4

Special Considerations

• Mild wheezing or a history of chronic obstructive pulmonary disease may allow for a trial of a reduced dose of metoprolol (e.g., 12.5 mg) rather than complete avoidance 6
• The European Society of Cardiology notes that beta blockers are only relatively contraindicated in asthma, with selective beta-1 blockers being preferred when necessary 1
• Some studies suggest that very low doses of metoprolol (≤100 mg daily) may be tolerated in some asthmatic patients, especially with concurrent optimal bronchodilator therapy 5, 7