Comparing neuroprotective drug efficacy in rodent neonatal brain injury models

BACKGROUND: A challenge in preclinical neonatal neuroprotection research is the implementation of study designs that enable direct comparison of multiple potentially effective drugs. We used adaptive design to test four FDA-approved drugs (azithromycin, erythropoietin, caffeine, and melatonin) concurrently and determine which best combined safety and efficacy. METHODS: exposure); some experiments included pre-treatment with agents that induced inflammation, and some included post-HI brief moderate hypothermia. Sensorimotor and neuropathology measures were incorporated into a Composite Score that also accounted for deaths. Outcome was initially evaluated at P21 and in confirmatory studies at P35. A pre-specified Bayesian algorithm with futility and efficacy stopping rules was devised to analyze emerging data and adjust subsequent animal allocation among drug groups. RESULTS: In all models, either azithromycin or erythropoietin (EPO) offered superior neuroprotection at P21, and the other was "runner-up". Caffeine and melatonin conferred modest neuroprotection in pure HI but were quickly eliminated in hypothermia-treated HI. At P35, azithromycin and EPO outcomes were generally similar. CONCLUSION: These results support azithromycin as a candidate neuroprotective agent that warrants future studies in large animal neonatal cerebral hypoxia-ischemia models. IMPACT: We used adaptive design to compare four repurposed drugs (azithromycin, caffeine, erythropoietin, and melatonin) in neonatal rodent brain injury. Key factors differentiating our approach from existing reports were within-litter comparisons, evaluation in multiple models, and measurement of both function and neuropathology. Either azithromycin or erythropoietin was the most neuroprotective in any given model, with the other a close "runner-up". Melatonin and caffeine were neuroprotective in pure HI, but less effective than azithromycin. In other models, they were less effective and eliminated early by the Bayesian algorithm. This supports azithromycin as a candidate neuroprotectant and supports future studies in large animal models.