The aim of this study was to prepare riboflavin laurate (RFL) nanosuspensions as an intramuscular injection for long-term riboflavin supplementation. Stable RFL nanosuspensions were obtained by injecting RFL/poloxamer solution in N,N-dimethyl formamide into a trehalose solution. Long soft nanostructures initially appeared and then tube-like rigid nanostructures were obtained after removal of solvents according to the transmission electron microscopic images. The nanosuspensions had narrow size distribution and the mean size was about 300 nm. Molecular self-assembly of RFL may drive the formation of nanostructures. RFL formed a monolayer at the air/water interface and poloxamer 188 could insert into the monolayer. The nanosuspensions were intramuscularly injected into rats to provide long-term riboflavin supplementation for more than 30 days in light of body weight, food intake, and urinary riboflavin. The nanosuspensions were also used to resist the riboflavin deficiency induced by methotrexate chemotherapy. RFL nanosuspensions are a promising nanomedicine for long-term riboflavin supplementation.
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