Allopurinol for preventing mortality and morbidity in newborn infants with hypoxic-ischaemic encephalopathy

Abstract

Delayed neuronal death following a perinatal hypoxic insult is due partly to xanthine oxidase-mediated production of cytotoxic free radicals. Evidence exists that allopurinol, a xanthine-oxidase inhibitor, reduces delayed cell death in experimental models of perinatal asphyxia and in people with organ reperfusion injury. To determine the effect of allopurinol on mortality and morbidity in newborn infants with hypoxic-ischaemic encephalopathy. We used the standard search strategy of the Cochrane Neonatal Group. We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, 2012, Issue 1), MEDLINE (1966 to March 2012), EMBASE (1980 to March 2012), CINAHL (1982 to March 2012), conference proceedings, and previous reviews. Randomised or quasi-randomised controlled trials that compared allopurinol administration versus placebo or no drug in newborn infants with hypoxic-ischaemic encephalopathy. We extracted data using the standard methods of the Cochrane Neonatal Review Group with separate evaluation of trial quality and data extraction by two review authors. We included three trials in which a total of 114 infants participated. In one trial, participants were exclusively infants with severe encephalopathy. The other trials also included infants with mild and moderately severe encephalopathy. These studies were generally of good methodological quality, but were too small to exclude clinically important effects of allopurinol on mortality and morbidity. Meta-analysis did not reveal a statistically significant difference in the risk of death (typical risk ratio 0.88; 95% confidence interval (95% CI) 0.56 to 1.38; risk difference -0.04; 95% CI -0.18 to 0.10) or a composite of death or severe neurodevelopmental disability (typical risk ratio 0.78; 95% CI 0.56 to 1.08; risk difference -0.14; 95% CI -0.31 to 0.04). The available data are not sufficient to determine whether allopurinol has clinically important benefits for newborn infants with hypoxic-ischaemic encephalopathy. Much larger trials are needed. Such trials could assess allopurinol as an adjunct to therapeutic hypothermia in infants with moderate and severe encephalopathy and should be designed to exclude important effects on mortality and adverse long-term neurodevelopmental outcomes.