In Vitro Uptake and Release of Natamycin From Conventional and Silicone Hydrogel Contact Lens Materials

OBJECTIVES: To investigate the uptake and release of the antifungal ocular drug, natamycin from commercially available conventional hydrogel (CH) and silicone hydrogel (SH) contact lens (CL) materials and to evaluate the effectiveness of this delivery method. METHODS: Five commercial SH CLs (balafilcon A, comfilcon A, galyfilcon A, senofilcon A, and lotrafilcon B) and four CH CLs (etafilcon A, omafilcon A, polymacon, vifilcon A) were examined in this study. These lenses were incubated with natamycin solubilized in dimethyl sulfoxide, and the release of the drug from these lenses, in Unisol 4 pH 7.4 at 32±1°C, was determined using UV-visible spectrophotometry at 305 nm over 24 hours. RESULTS: There was a significant uptake of natamycin between 0 hour and 24 hours (P<0.05) for all CL materials. However, there was no significant difference between any of the lens materials, regardless of their composition (P>0.05). There was a significant difference in release between all the SH materials (P<0.05) and CH materials (P<0.05). All CL materials showed a significant increase in the release of natamycin until 1 hour (P<0.05), which was followed by a plateau (P>0.05). Overall, the release of natamycin was higher in CH than SH lenses (P<0.001). CONCLUSIONS: All CLs released clinically relevant concentrations of natamycin within 30 minutes, but this release reached a plateau after approximately 1 hour. Further CL material development will be necessary to produce a slow and sustained drug releasing device for the delivery of natamycin.