A premature neonate born at 29 weeks has a haemodynamically significant patent ductus arteriosus with bounding pulses and a wide pulse pressure. The drug chosen to close the ductus acts by:
- A Inhibiting prostaglandin synthesis, removing the vasodilator tone that keeps the ductus open ✓
- B Blocking beta-adrenergic receptors in the ductal smooth muscle
- C Stimulating alpha-adrenergic receptors to constrict the ductal lumen
- D Antagonising nitric oxide signalling in the pulmonary vasculature
Correct answer: A. Inhibiting prostaglandin synthesis, removing the vasodilator tone that keeps the ductus open
Explanation
The fetal ductus arteriosus is held open by prostaglandins, chiefly PGE1 and PGE2, acting on EP4 receptors in ductal smooth muscle. Indomethacin or ibuprofen inhibit cyclooxygenase, so prostaglandin levels fall and the duct constricts. Beta blockers and alpha agonists have no role in ductal closure. Conversely, in a neonate with a duct-dependent cyanotic lesion such as transposition, IV alprostadil (PGE1) is given to keep the ductus open.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.