Which drug is used to maintain patency of the ductus arteriosus in infants with ductal dependent cardiac defects?

• A. Indomethacin
• B. Ibuprofen
• C. Alprostadil (Prostaglandin E1)
• D. Erythromycin

Answer: (C)

Maintaining ductus arteriosus patency in ductal-dependent defects requires keeping prostaglandin signaling active to keep the canal open. Alprostadil (Prostaglandin E1) is the prostaglandin analog used for this purpose because it relaxes the smooth muscle of the ductus arteriosus and prevents its closure, ensuring continued flow for either pulmonary or systemic circulation until a corrective repair can be performed.

Indomethacin and ibuprofen work oppositely; they inhibit prostaglandin synthesis and promote closure of the ductus, which is helpful when patency is not needed but would be harmful if the defect relies on an open ductus. Erythromycin is an antibiotic and does not influence ductus arteriosus patency.