A premature neonate born at 30 weeks has a haemodynamically significant patent ductus arteriosus. Which NSAID is conventionally used to close the ductus, and what is its mechanism?
- A Celecoxib, selectively blocking endothelial COX-2
- B Aspirin, irreversibly acetylating cyclooxygenase and reducing thromboxane A2
- C Indomethacin, inhibiting prostaglandin E synthesis and removing the vasodilator tone maintaining ductal patency ✓
- D Ketorolac, blocking peripheral sensitisation of ductal nociceptors
Correct answer: C. Indomethacin, inhibiting prostaglandin E synthesis and removing the vasodilator tone maintaining ductal patency
Explanation
Patency of the fetal ductus arteriosus depends on prostaglandin E1 and prostacyclin produced locally. At birth, rising oxygen normally suppresses this, but in prematurity the duct remains open. Indomethacin or intravenous ibuprofen inhibit prostaglandin synthesis and allow constriction and closure. Thromboxane C2 is a platelet vasoconstrictor unrelated to ductal tone, which eliminates option B despite aspirin being a classic COX-1 inhibitor.
Reference: Nelson Textbook of Pediatrics, 21st ed.
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