Neonatal Hypoxic-Ischemic Encephalopathy (HIE), a brain disease due to brain hypoxia along with ischemia and reduced cerebral blood flow, is one of the primary reasons of severe injury among babies prematurely born. No efficacy treatment is available to the present day. Estetrol (E4), a major estradiol metabolite, has an important role in the brain development and protection. The aim of this study is to develop new injectable liposome and drug-in-cyclodextrin-in-liposome (DCL) formulations, encapsulating E4 in order to enhance its crossing through the blood-brain barrier (BBB). Liposome and DCL formulations were prepared and were physiochemically characterized. Stability in foetal bovine serum (FBS) was evaluated. LDH and MTS tests on endothelial, neuronal and BBB model cells, as well as hemocompatibility of the nanovectors were performed in vitro. In vitro BBB passage was evaluated using human BBB cell line (hCMEC/D3). All the formulations had average particle size below 150 nm, polydispersity index below 0.10 and ζ potential around +30 mV. The encapsulation efficacy for liposomes was between 3% and 10% while those of DCL are between 15% and 35%. The effect of liposome and DCL formulations on cell viability and integrity was evaluated. The results showed no toxic effects on all the tested cell lines. Hemocompatibility tests showed no hemolysis, platelet aggregation or effects on coagulation, confirming the possibility of the formulations to be intravenously administrated. BBB passage tests highlighted the capability of the formulations to pass the BBB and reach the brain. Therefore, the formulations are promising drug delivery system to target estrogens to the brain, due to their physiochemical characteristics.