Abstract

Background: Amphotericin B (AMB) is water-insoluble polyene, which has a broad spectrum of antifungal activity. The hydrophobic drug only exits in the phospholipid bilayer, leading to a low-drug liposomal loading capacity.

Objectives: This study is designed to prepare water-soluble inclusion complex (IC) between AMB and cyclodextrin (CD) to formulate liposomal vesicles, double-loaded with drug molecules in the phospholipid bilayer and AMB/CD IC in the aqueous core.

Methods: Water-soluble AMB/CD IC was prepared by pH adjustment of the aqueous media and consequently characterized by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Liposomes double-loaded with AMB were formulated by the thin-film hydration method and accordingly evaluated for vesicle size, polydispersity index, entrapment efficiency, zeta potential, and in vitro drug leakage.

Results: Hydroxypropyl β cyclodextrin (HP-β-CD) better solubilized AMB than both α-CD and β- CD e.g., the concentration of water-soluble AMB/HP-β-CD IC could reach 465 μg/mL. Both DSC and SEM data illustrated that the drug no longer existed in its crystalline form, in AMB/HP-β-CD IC. Liposomes double-loaded with hydrophilic AMB/HP-β-CD IC and hydrophobic AMB had a diameter of 270 nm, polydispersity index less than 0.27, and zeta potential ca.-42.8 mV. Moreover, liposomes double-loaded with AMB enhanced drug-liposomal loading capacity by 25%, less leaked drug in phosphate buffer pH 7.4 at 37°C in comparison to liposomes loaded with only hydrophobic AMB.

Conclusion: Liposomes double-loaded with AMB and AMB/HP-β-CD IC increased drug-encapsulation ability and in vitro stability, suggesting potential drug delivery systems.

Keywords: Amphotericin B, liposomes, double encapsulated, drug delivery, cyclodextrin, hydroxypropyl-beta-cyclodextrin.

Graphical Abstract