Haemoglobin vesicles (HbVs) (product name, NMU-HbVs [Nara Medical University-Haemoglobin Vesicles]), which contain purified human haemoglobin encapsulated within liposomes, have been developed as a potential alternative to blood transfusions in emergency situations. A previous phase I study examined doses up to 100 mL in 11 healthy volunteers. Here, we describe the protocol for a phase Ib study, wherein we will evaluate the safety and pharmacokinetics of NMU-HbV in healthy Japanese adults.

This single-centre, open-label, dose-escalation study will enrol 16 healthy volunteers divided into four cohorts. Planned doses are 100 mL for cohorts 1 and 2, 200 mL for cohort 3 and 400 mL for cohort 4, with infusion rates gradually increasing to a maximum of 5.0 mL/min. The primary endpoint will be safety, which will be assessed as the incidence of adverse events within 14 days and significant clinical changes within 72 hours after administration. Safety evaluations will include subjective symptoms, vital signs, electrocardiograms and laboratory test results compared with the baseline. The secondary endpoint will be pharmacokinetics, which will be assessed as changes in NMU-HbV concentration immediately after infusion until day 4 to determine the maximum blood concentration, time to reach the maximum blood concentration, area under the blood concentration-time curve and elimination half-life. This study will provide data on the safety and pharmacokinetic profiles of NMU-HbV at doses up to 400 mL. The findings are expected to support the further development of NMU-HbV as a viable alternative to emergency transfusions.

The study protocol was approved by the Institutional Review Board of Nara Medical University on 10 December 2024. Dissemination plans include publishing in peer-reviewed scientific journals and presentation at international conferences.

Japan Registry of Clinical Trials (jRCT2051240249). Registered on 27 January 2025 (https://jrct.mhlw.go.jp/en-latest-detail/jRCT2051240249).