Cyclodextrin-polysaccharide-based, in situ-gelled system for ocular antifungal delivery

Abstract

Fluconazole was studied with two different hydrophilic cyclodextrins (hydroxypropyl-β-cyclodextrin (HPBCD) and sulfobutyl ether-β-cyclodextrin (SBECD)) for the formation of inclusion complexes. HPBCD and SBECD showed low cell cytotoxicity in human keratocytes as assessed by the label-free xCELLigence system for real-time monitoring. The fluconazole-HPBCD complex was incorporated into an ion-sensitive ophthalmic gel composed of the natural polysaccharides gellan gum and κ-carrageenan. This system showed good bioadhesive properties and effective control of fluconazole release.

Keywords: cyclodextrins; eye drops; fluconazole; hydroxypropyl-β-cyclodextrin; sulfobutylether-β-cyclodextrin.

Figure 1

Phase solubility diagrams for fluconazole obtained with β-cyclodextrin derivatives at 25 °C in water (mean ± SD, n = 6). The dotted lines indicate the necessary CD concentration required to solubilize 10 mg/mL of fluconazole.

Figure 2

Solubility of fluconazole in aqueous solutions containing 5% of CD and 0.5% of the respective polysaccharide.

Figure 3

Ocular cytotoxicity studies of HPBCD and SBECD in primary corneal human keratocytes, using real-time xCELLigence impedance analysis. (a) Kinetic curve survival rates for HPBCD; (b) Kinetic curve survival rates for SBECD; (c) Evolution of IC₅₀ vs time for HPBCD and SBECD. IC₅₀ values at each time were calculated using (a) and (b); IC₅₀ represents the concentration that causes a reduction in the survival of 50% of the cells.

Figure 4

Ocular cytotoxicity studies of fluconazole in primary corneal human keratocytes obtained using real-time xCELLigence impedance analysis. (a) Kinetic curve survival rates; (b) evolution of IC₅₀ vs time.

Figure 5

HET-CAM assay: (a) positive Control (NaOH 0.1 N); (b) negative control (NaCl 0.9%); (c) HPBCD 10 mg/mL; (d) SBECD 10 mg/mL; (e) fluconazole (2 mg/mL). Photographs show the status of the vessel at the end of the experiment.

Figure 6

Bioadhesive properties (bioadhesion work and maximum force of detachment) of ion-sensitive hydrogels using tanned leather as a substrate (mean ± SD, n = 6).

Figure 7

Release profiles of fluconazole in simulated tear fluid from the gels with (closed symbols) or without (open symbols) HPBCDs and different proportions of polysaccharides (mean ± SEM, n = 3).