During a chart review, you notice a 58-year-old woman with generalized anxiety disorder — maintained on escitalopram 20 mg daily — was just prescribed azithromycin 500 mg then 250 mg × 4 days for acute bronchitis by an urgent care NP earlier today. Her prior ECG shows a QTc of 465 ms. Which of the following best describes the most important drug-interaction concern, and the most appropriate response?

Question

Accepted Answer

✅ B. Azithromycin and escitalopram both prolong the QT interval — the additive risk of torsades is the main concern; consider stopping azithromycin and using doxycycline instead.
Correct. Azithromycin (macrolide) and the SSRIs citalopram/escitalopram are both QT-prolonging drugs. Combining them — especially with a baseline QTc of 465 ms (already borderline/elevated) in an older female patient — substantially raises the risk of torsades de pointes. The most appropriate response is to avoid the combination: hold/stop the azithromycin and use a non-QT-prolonging alternative such as doxycycline (if antibiotics are truly indicated for acute bronchitis, which is often viral).

❌ A. The combination is safe; azithromycin has no meaningful QT effect and no action is needed.
Incorrect. Azithromycin does prolong the QT interval and has an FDA warning for associated torsades de pointes, especially in patients with other risk factors. It is not QT-neutral.

❌ C. The main concern is serotonin syndrome; hold the escitalopram until the azithromycin course is complete.
Incorrect. Azithromycin is not a serotonergic agent and does not meaningfully raise serotonin syndrome risk. The concern here is QT prolongation, not serotonin toxicity.

❌ D. The main concern is azithromycin-induced hepatotoxicity; order LFTs and continue both drugs.
Incorrect. While severe hepatic AEs are rare with azithromycin, they are not the primary drug-interaction issue with a patient on escitalopram and a borderline-long QTc. QT additivity is the headline concern.

Azithromycin

✅ Indications

⚙️ Mechanism of Action

📏 Dosing

🚫 Contraindications

⚠️ Adverse Effects

🔬 Monitoring

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