Hemolytic toxicity caused by primaquine (PQ) is a high-risk condition that 
hampers the wide use of PQ to treat liver-stage malaria. This study demonstrated 
that phospholipid-free small unilamellar vesicles (PFSUVs) composed of Tween80 
and cholesterol could encapsulate and deliver PQ to the hepatocytes with reduced 
exposure to the red blood cells (RBCs). Nonionic surfactant (Tween80) and 
cholesterol-forming SUVs with a mean diameter of 50 nm were fabricated for 
delivering PQ. Drug release/retention, drug uptake by RBCs, pharmacokinetics, 
and liver uptake of PFSUVs-PQ were evaluated in invitro and invivo models in 
comparison to free drugs. Additionally, the stress effect on RBCs induced by 
free PQ and PFSUVs-PQ was evaluated by examining RBC morphology. PFSUVs provided 
>95% encapsulation efficiency for PQ at a drug-to-lipid ratio of 1:20 (w/w) and 
stably retained the drug in the presence of serum. When incubated with RBCs, PQ 
uptake in the PFSUVs group was reduced by 4- to 8-folds compared to free PQ. As 
a result, free PQ induced significant RBC morphology changes, while PFSUVs-PQ 
showed no such adverse effect. Intravenously (i.v.) delivered PFSUVs-PQ produced 
a comparable plasma profile as free PQ, given i.v. and orally, while the liver 
uptake was increased by 4.8 and 1.6-folds, respectively, in mice. Within the 
liver, PFSUVs selectively targeted the hepatocytes, with no significant blood or 
liver toxicity in mice. PFSUVs effectively targeted PQ to the liver and reduced 
RBC uptake compared to free PQ, leading to reduced RBC toxicity. PFSUVs 
exhibited potential in improving the efficacy of PQ for treating liver-stage 
malaria.