What antihypertensive drug is most likely to cause adverse effects in a patient with chronic obstructive pulmonary disease (COPD) and mild arterial insufficiency of the lower extremities?

Beta-Blockers Are Most Likely to Cause Adverse Effects in This Patient with COPD and Peripheral Arterial Disease

The beta-adrenergic blocking agent (option C) is most likely to cause adverse effects in this 72-year-old man with COPD and peripheral arterial disease.

Rationale for Avoiding Beta-Blockers in This Patient

Impact on COPD

Beta-blockers can significantly worsen pulmonary function in patients with COPD through several mechanisms:

• They antagonize the bronchodilatory effects of endogenous catecholamines and exogenous β-agonists (which this patient is currently using for COPD treatment) 1
• Even selective β1-blockers can lose their cardioselectivity at higher doses, potentially causing bronchospasm 2
• They may reduce the therapeutic benefits of the patient's current inhaled bronchodilator therapy 3

The 2017 GOLD guidelines specifically note that while selective β1-blockers can be used cautiously in certain COPD patients with specific cardiovascular indications, they must be used with extreme caution in patients whose COPD is being actively treated with β-agonists 1.

Impact on Peripheral Arterial Disease

Beta-blockers can also exacerbate the patient's arterial insufficiency of the lower extremities by:

• Reducing peripheral blood flow through decreased cardiac output
• Causing peripheral vasoconstriction, particularly with non-selective agents
• Potentially worsening claudication symptoms 1

The patient already has decreased pedal pulses bilaterally, indicating compromised circulation to the lower extremities that could be further impaired by beta-blocker therapy.

Evaluation of Other Antihypertensive Options

Safer Alternatives for This Patient

1. Calcium Channel Blockers (option E): Generally well-tolerated in COPD patients with no negative effects on bronchomotor tone 4. They are considered among the best initial choices for hypertension treatment in COPD patients.

2. Angiotensin-Converting Enzyme (ACE) Inhibitors (option D): Do not adversely affect pulmonary function and may have beneficial effects on both cardiovascular and pulmonary systems 4.

3. Alpha-Adrenergic Blocking Agents (option B): May actually improve peripheral blood flow, which could benefit the patient's arterial insufficiency 1.

4. Vasodilators (option H): Can improve peripheral circulation, though careful monitoring for hypotension is necessary 5.

Potential Issues with Other Antihypertensive Classes

• Alpha-2 Adrenergic Agonists (option A): May cause significant CNS adverse effects, especially in older adults, and are generally reserved as last-line agents 1.

• Diuretics (options F and G): While generally acceptable in COPD, they require careful monitoring, especially in elderly patients. Loop diuretics are preferred in patients with heart failure but may not be first-line for uncomplicated hypertension 1.

Clinical Decision Algorithm

1. Avoid beta-blockers (both selective and non-selective) due to high risk of worsening COPD and peripheral arterial disease

2. Consider as first-line options:

   • Calcium channel blockers (particularly dihydropyridines)
   • ACE inhibitors
   • Angiotensin II receptor blockers

3. Consider as second-line options:

   • Alpha-1 blockers (may benefit peripheral circulation)
   • Diuretics (with careful monitoring)

4. Avoid or use with extreme caution:

   • Beta-blockers
   • Centrally acting agents (alpha-2 agonists)

Important Monitoring Considerations

If beta-blockers must be used for a compelling indication (which is not apparent in this case):

• Use only highly selective β1-blockers at the lowest effective dose
• Monitor closely for worsening respiratory symptoms
• Start at low doses with very gradual titration
• Ensure patient is stable on optimal COPD therapy before initiation
• Have a low threshold for discontinuation if respiratory status deteriorates 6

In conclusion, beta-blockers represent the antihypertensive class most likely to cause adverse effects in this patient with COPD and peripheral arterial disease, potentially worsening both conditions and compromising the patient's quality of life and functional status.