How do you close a patent ductus arteriosus pharmacologically?

• A. Prostaglandin E1
• B. Ibuprofen
• C. Acetazolamide
• D. Indomethacin

Answer: (D)

Prostaglandins keep the ductus arteriosus patent after birth, so closing it pharmacologically means reducing prostaglandin synthesis. Indomethacin does this by inhibiting cyclooxygenase, lowering levels of prostaglandins like PGE2 that keep the ductus open. With less prostaglandin signaling, the smooth muscle of the ductus arteriosus constricts and the vessel closes, which is why indomethacin is the classic first-line treatment for closing a patent ductus arteriosus in preterm infants. Prostaglandin E1 would actually keep the ductus open, not close it, so it isn’t used for closure. Acetazolamide isn’t a relevant agent for PDA closure, and while ibuprofen is another NSAID that can close the ductus, indomethacin is the standard choice emphasized in this context.