Abstract
Purpose:
The antifungal agent natamycin can effectively form inclusion complexes with beta-cyclodextrin (β-CD) to improve the water solubility of natamycin by 16-fold (Kloontz, J. Agric. Food.Chem. 2003). The purpose of this study was to develop contact lens (CL) materials functionalized with methacrylated β-CD, and to evaluate their ability to deliver natamycin in vitro.
Methods:
Varying amounts of di-methacrylated β-CD (0, 5, 7.5, 10, 12.5% of total monomer weight) were added to a monomer solution containing N,N-dimethylacrylamide (DMAA), [Tris(trimethylsiloxy)silyl]-propyl methacrylate (TRIS) and ethylene glycol dimethacrylate (EGDMA). The mixtures were then pipetted into CL moulds and were polymerized by photoinitiation. The resulting five CL materials were hydrated in 5 mL of PBS for 24 hours (h), followed by incubation with a 4 mL methanol solution containing 0.5 mg/mL of natamycin for 24 h at room temperature. The release of natamycin from these materials in 10 mL of PBS, pH 7.4 at 32±2oC was monitored using UV-Visible spectrophotometry at 304 nm over 48 h.
Results:
The uptake of the drug was not monitored, as concentrations above 100 μg/mL were beyond the linear ranges of detection. The release of natamycin by all model CL materials increased between 0 and 12 h, and reached a plateau thereafter (p<0.05). After 24 h of release, the CL material containing 7.5 % di-methacrylated β-CD initial loading had the highest amount of the drug released (117 μg/mL). CL materials containing 10% and 12.5% initial β-CD released 68 μg/mL and 65 μg/mL of natamycin respectively. By visual inspection, materials containing 12.5 % β-CD showed a decrease in transparency, however there was no reduction in transparency for other materials.
Conclusions:
CL materials functionalized with 7.5% of di-methacrylated β-CD initial loading released more drug than the control materials. Further, addition of β-CD resulted in materials with less drug delivery efficiency, likely resulting from unfavourable chain interactions, which hinders the binding of natamycin to β-CD. Future work with γ-CD, which has been reported to increase the water solubility of natamycin by 73-fold, may produce better drug delivery CL materials.
Keywords: 477 contact lens •
422 antibiotics/antifungals/antiparasitics