Which medication is commonly used to pharmacologically close a patent ductus arteriosus in preterm infants?

• A. Indomethacin
• B. Penicillin
• C. Furosemide
• D. Morphine

Answer: (A)

In preterm infants, the ductus arteriosus stays open because of circulating prostaglandins, especially PGE2. To close it pharmacologically, you want to reduce prostaglandin production. Indomethacin is a nonsteroidal anti-inflammatory drug that inhibits cyclooxygenase, lowering prostaglandin synthesis. With less PGE2, the ductus arteriosus constricts and typically closes within 24–48 hours. This makes indomethacin a common first-line medical therapy for a hemodynamically significant PDA in prematurity.

Other options don’t accomplish this effect: penicillin is an antibiotic, not a vessel-closure agent; furosemide is a diuretic used for fluid management and does not close the PDA; morphine is an analgesic and has no role in promoting ductal closure. Indomethacin, however, must be used with awareness of potential risks like renal impairment or NEC, so renal function and GI status are monitored during treatment.