A premature neonate born at 29 weeks gestation develops a wide pulse pressure, bounding peripheral pulses and a continuous machinery murmur at the left infraclavicular area on day 5. Echocardiography confirms a patent ductus arteriosus. The most appropriate pharmacological action targets which pathway?

• A Inhibition of cyclooxygenase-mediated prostaglandin synthesis ✓
• B Inhibition of nitric oxide synthase in ductal endothelium
• C Blockade of beta-adrenergic receptors in ductal smooth muscle
• D Antagonism of bradykinin at ductal smooth muscle receptors

Explanation

Ductal patency is actively maintained by locally produced prostaglandin E acting on ductal smooth muscle. In the preterm infant the ductus remains unusually sensitive to prostaglandins, so indomethacin or ibuprofen, both cyclooxygenase inhibitors, reduce prostaglandin synthesis and promote closure. Nitric oxide also relaxes the ductus but is not the target of standard pharmacological closure, and adrenergic blockade has no established role.

Reference: Ganong's Review of Medical Physiology, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.