A Novel Amphotericin B Hydrogel Composed of Poly(Vinyl Alcohol)/Borate Complex for Ophthalmic Formulation

In this study, we developed a water-soluble complex-hydrogel viscosity-controlled formulation of amphotericin B (AmB). AmB is insoluble in water, but borax makes it soluble by forming a complex with AmB. Borax also forms complexes with poly(vinyl alcohol) (PVA) to produce viscous hydrogels. Furthermore, boric acid interacts with mucin expressed in corneal epithelial cells. Accordingly, by utilizing these properties of borax simultaneously, we prepared a water-soluble AmB complex-hydrogel with poly(vinyl alcohol)/borate (PVA-B-AmB), which is suitable for eye drops. PVA-B-AmB was easily prepared by simply mixing aqueous AmB solution dissolved in borax, PVA solution, and water. The 11B-NMR results suggested that PVA-B-AmB existed by bonding PVA and AmB via boronic acid. PVA-B-AmB (gel ratio = 0.55) has a viscosity of 18.3 ± 0.5 mPa·s and is suitable for ophthalmic formulations. This formulation exhibited sustained release of AmB of approximately 45% at 24 h. It was also shown that this formulation interacts with mucin. These results suggest that PVA-B-AmB can be used as a water-soluble AmB preparation suitable for ophthalmic use.