Certified Ophthalmic Medical Technologist (COMT) Practice Exam

What drug classification is associated with systemic absorption leading to bronchial smooth muscle contraction?

1. Alpha agonists

2. Beta-blockers

3. Calcium channel blockers

4. Antihistamines

The correct answer is: Beta-blockers

The correct classification associated with systemic absorption leading to bronchial smooth muscle contraction is beta-blockers. Beta-blockers primarily block the action of adrenaline on beta-adrenergic receptors. While their main use is to decrease heart rate and blood pressure, they have a notable effect on the respiratory system as well. In the lungs, beta-2 adrenergic receptors, when activated, promote bronchial dilation. Conversely, beta-blockers inhibit these receptors. When systemic absorption occurs, this inhibition can lead to bronchoconstriction, especially in patients with underlying respiratory issues, such as asthma or chronic obstructive pulmonary disease (COPD). This is why beta-blockers carry a warning for patients with reactive airway diseases. Other classifications do not have this same systemic effect on bronchial smooth muscle. Alpha agonists primarily act on alpha receptors and can cause vasoconstriction but do not have a direct role in bronchial muscle contraction. Calcium channel blockers mainly affect vascular smooth muscle and cardiac myocytes, and their main indications involve cardiovascular conditions, not bronchial reactivity. Antihistamines are used to counteract allergic reactions and do not directly cause bronchoconstriction; instead, they often counteract processes that lead to bronchial contraction due to allergens