A premature neonate born at 29 weeks has a haemodynamically significant patent ductus arteriosus with bounding peripheral pulses and a wide pulse pressure. The drug of choice to induce pharmacological closure of the ductus works by:
- A Blocking beta-1 adrenergic receptors on ductal smooth muscle
- B Inhibiting prostaglandin synthesis, removing the vasodilator that keeps the ductus open ✓
- C Stimulating alpha-adrenergic receptors to constrict the ductus directly
- D Antagonising nitric oxide mediated relaxation of ductal tissue
Correct answer: B. Inhibiting prostaglandin synthesis, removing the vasodilator that keeps the ductus open
Explanation
Patency of the ductus arteriosus in fetal and neonatal life is maintained by prostaglandin E1 (and prostacyclin) produced locally by ductal tissue. Indomethacin or ibuprofen inhibit cyclooxygenase, reduce PGE synthesis, and allow ductal constriction. The key distractor is alpha stimulation: although catecholamines raise systemic pressure, they do not close the ductus, and ductal tone depends specifically on the balance of PGE versus oxygen tension.
Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.