Plackett-Burman design for screening of critical variables and their effects on the optical transparency and swelling of gatifloxacin-Pluronic-loaded contact lens

The optical and swelling properties of gatifloxacin-loaded contact lens decrease owing to the precipitation of gatifloxacin (on hydration) in the matrix structure of the contact lens. This paper focuses on the use of Pluronic F68 both inside and outside (in the packaging solution) the contact lens to form micelles to dissolve the gatifloxacin precipitates and not limited to sustain the release of gatifloxacin. The aim of this study was to screen the critical variables affecting the optical and swelling properties of gatifloxacin-loaded contact lens. The independent variables investigated were the concentration of Pluronic F68 incorporated in the monomer solution to fabricate the lens (X ₁, %w/v), the concentration of Pluronic F68 in the packaging solution (X _2, %w/v), the concentration of gatifloxacin incorporated in the monomer solution (X _3, %w/v), the concentration of gatifloxacin incorporated in the packaging solution during autoclave (X ₄, %w/v), the concentration of gatifloxacin incorporated in the packaging solution during extraction (X ₅, %w/v), the time (stabilization time) after the addition of gatifloxacin and Pluronic F68 to the monomer solution before the fabrication of the lens (X ₆, h), the pH of the packaging solution (X ₇), the temperature of the extracted solution (X ₈, °C), and the curing time for fabricating the contact lens (X ₉, min). The gatifloxacin-loaded contact lenses were characterized for their optical transmittances after sterilization on day 1 (Y ₁, %), optical transmittances after 7 days of sterilization (Y ₂, %) and swelling percentages after 7 days of sterilization (Y ₃, %). The selected variables showed responses that were in the ranges 53.5% to 97.2%, 51.3% to 92.6%, and 50.3% to 83.7% for Y ₁, Y ₂, and Y ₃, respectively. The data suggest that the presence of Pluronic F68 inside the contact lens (X ₁) reduced the optical and swelling properties of the contact lens, whereas the presence of Pluronic F68 in the packaging solution (X ₂) improved them through micelle formation. The other variables (X ₃ to X ₉) did not exhibit significant effects on the swelling and transmittance. This study revealed the potential of Plackett-Burman design to screen the selected critical variables that affected the optical and swelling properties of gatifloxacin-loaded contact lens.