We investigated the effects of clinically comparable doses of ibuprofen and indomethacin on renal, gastrointestinal and cerebral perfusion in newborn piglets, and hypothesized that ibuprofen would have less effect on regional circulations. Methods: Fentanyl anesthetized 1 to 3 day old piglets were instrumented with a pulmonary artery catheter, a femoral arterial catheter and a carotid arterial catheter advanced into the left ventricle for administration of microspheres. Animals were randomly assigned to receive ibuprofen (20 mg/kg, n = 8), indomethacin (0.3 mg/kg, n = 7) or vehicle (n = 6). Fluorescent microspheres were injected prior to and at 20, 40, 60, 90 and 120 minutes after drug administration. Regional blood flow and vascular resistance were calculated; relative resistance at the indicated times was calculated from resistance values prior to drug injection. Results: Heart rate, blood pressure, cardiac output, and systemic and pulmonary vascular resistances were not affected by the drugs. Blood gases were also unaffected by either drug or vehicle. Baseline blood flows were: kidney cortex= 464 (SD 29); duodenum/jejunum = 155 (SD 32); ileum = 108 (SD 22); colon = 109 (SD 14.7); cerebral cortex = 91 (SD 17); brainstem = 71 (SD 12) [all mL/min/100g tissue].

Ibuprofen increased renal cortical and medullary resistance by 44 and 52% maximally at 90 and 120 minutes post-injection, respectively (p < 0.05) and decreased renal blood flow at these times. However, ibuprofen had no significant effects on gastrointestinal or cerebral resistance or blood flow.

Indomethacin increased renal cortical and medullary resistance by 66 and 71% at 60 minutes post-injection, respectively (p < 0.05) and decreased renal blood flow. Indomethacin raised duodeno-jejunal, ileal and colon resistance by 97, 102 and 75% at 60 minutes, respectively (p < 0.05) and decreased bowel blood flow. Indomethacin raised cerebral cortical, cerebellar and periventricular white matter resistance by 92, 86 and 72% at 90 minutes (p< 0.05), but had no effect on brainstem resistance. Blood flow to the cerebral cortex, cerebellum and periventricular white matter was also decreased. Conclusion: Ibuprofen and indomethacin both lead to renal vasoconstriction. However, indomethacin increases gastrointestinal and cerebral vascular resistance, whereas ibuprofen has no effect in these circulations, suggesting it may be a valuable clinical alternative.