Optimized acriflavine-loaded lipid nanocapsules as a safe and effective delivery system to treat breast cancer.

Acriflavine (ACF) hydrochloride is currently repurposed as multimodal drug, inhibiting hypoxia-inducible factors (HIF) pathways and exerting cytotoxic properties. The aim of this study was to encapsulate ACF in reverse micelles and to incorporate this suspension in lipid nanocapsules (LNC). Designs of experiments were used to work under quality by design conditions. LNC were formulated using a phase-inversion temperature method, leading to an encapsulation efficiency around 80%. In vitro, the encapsulated drug presented similar cytotoxic activity and decrease in HIF activity in 4T1 cells compared to the free drug. In vivo, ACF-loaded nanoparticles (ACF dose of 5 mg/kg) demonstrated a higher antitumor efficacy compared to free ACF on an orthotopic model of murine breast cancer (4T1 cells). Moreover, the use of LNC allowed to drastically decrease the number of administrations compared to the free drug (2 versus 12 injections), suppressing the ACF-induced toxicity.