Pharmacology · patient case question
What is the mechanism of action shared by albuterol and salmeterol?
Patient case: Asthma on two inhalers, with posterior teeth planned for implants
Patient: Male, 48 years old
Chief Complaint: “I want implants to replace the two teeth I lost.”
Background: Asthma, well controlled. Uses ALBUTEROL as a rescue inhaler and SALMETEROL twice daily with an inhaled corticosteroid. Last attack over a year ago. No other medical history.
Vital Signs: BP 126/78 mmHg · HR 74 bpm · RR 16 · SpO₂ 98%
Findings: Teeth #5 and #30 missing for several years. Clinical photographs show a POSTERIOR OPEN BITE, with the unopposed teeth in the opposing arches SUPRA-ERUPTED into the edentulous spaces. Radiographs show good bone height and volume at both sites. Periodontium healthy.
Show answer and explanation
Correct answer: B. Beta-2 adrenergic AGONIST
- A. Muscarinic antagonists such as ipratropium and tiotropium ARE used in obstructive airway disease, but through a different receptor entirely, and neither of these two drugs belongs to that class.
- B. CORRECT. Both are BETA-2 ADRENERGIC AGONISTS. Beta-2 receptors on bronchial smooth muscle are Gs-coupled: stimulation raises cyclic AMP, which relaxes the muscle and relieves bronchoconstriction. They differ only in kinetics — ALBUTEROL is a SHORT-acting beta agonist (SABA), the rescue inhaler that works within minutes and is what you reach for in an office asthma attack; SALMETEROL is a LONG-acting beta agonist (LABA), used twice daily for maintenance and USELESS in an acute attack because of its slow onset. A LABA must never be used without an inhaled corticosteroid.
- C. Beta-1 receptors are predominantly cardiac. A beta-1 agonist such as dobutamine increases heart rate and contractility and does nothing for the airway.
- D. A beta-2 BLOCKER is the opposite of what an asthmatic needs — non-selective beta blockade with propranolol can precipitate severe bronchospasm, which is why it is avoided in asthma.
Note: Dental consequences of chronic inhaler use worth knowing: XEROSTOMIA with raised caries risk from the beta-2 effect on salivary flow; ORAL CANDIDIASIS from the inhaled corticosteroid, prevented by rinsing after each dose; and enamel erosion from the low pH of some formulations. Have the patient bring the rescue inhaler to every appointment, and keep it on the bracket table.