Neuren Pharmaceuticals (ASX:NEU) said that the US Food and Drug Administration (FDA) generally accepted the investigational new study-opening clinical study of the pharmacokinetics, tolerability and safety of its NNZ-2591 drug candidate for one month in neonates and infants with hypoxic ischemic encephalopathy and the doses to be evaluated, guiding the inclusion/exclusion criteria and safety monitoring, according to a Wednesdday Australian bourse filing.

The regulator requested that the firm provide additional juvenile animal study data to support NNZ-2591 dosing in neonatal participants prior to initiating the clinical study. It also encouraged Neuren to submit a future meeting request to discuss appropriate endpoints, study population, and safety monitoring for a subsequent study.

The US FDA's feedback indicated that in a controlled trial to demonstrate the efficacy of NNZ-2591 in the treatment of Pitt Hopkins syndrome, a Pitt Hopkins syndrome-specific clinical global impression scale may be used as a co-primary endpoint if it is accompanied by an observer-reported functional outcome measure.

The firm plans to initiate both trials within the year.