A premature neonate born at 29 weeks gestation has a haemodynamically significant patent ductus arteriosus with bounding peripheral pulses and a wide pulse pressure. The drug used to induce pharmacological closure and the prostaglandin whose synthesis it blocks are:

• A Prostaglandin E1 infusion, maintaining ductal patency
• B Indomethacin, blocking prostaglandin E2 synthesis ✓
• C Paracetamol, blocking nitric oxide synthesis
• D Ibuprofen, blocking thromboxane A2 synthesis

Explanation

The ductus arteriosus remains open in fetal life because of prostaglandin E2 produced locally and circulating from the placenta. Indomethacin, a non-selective COX inhibitor, suppresses PGE2 synthesis and promotes ductal constriction. Intravenous ibuprofen is also used for this purpose but acts through general COX inhibition, not selective thromboxane blockade. PGE1 infusion does the opposite, keeping the duct open in duct-dependent congenital heart lesions.

Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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