A preterm baby of 28 weeks gestation with respiratory distress syndrome is admitted to the neonatal intensive care unit. On day 2 of life, the characteristic murmur of a patent ductus arteriosus (PDA) is heard, with the diagnosis confirmed by Doppler echocardiography. The attending neonatologist orders a course of indomethacin in an attempt to treat the PDA. The astute paediatric resident has just taken two tablets of ibuprofen to treat his post-call headache, and wonders whether this alternative non-steroidal anti-inflammatory drug might be just as efficacious, with less side …