Supercritical loading of gatifloxacin into hydrophobic foldable intraocular lenses - Process control and optimization by following in situ CO sorption and polymer swelling.

The supercritical impregnation process was used as a green technology for the elaboration of drug delivery intraocular lenses to mitigate the risk of post-operatory endophthalmitis after cataract surgery. Commercially available hydrophobic acrylic (copolymer of benzyl methacrylate and methyl methacrylate) intraocular lenses (IOLs) were impregnated with gatifloxacin, a fourth generation fluoroquinolone drug, using pure supercritical CO (scCO) to obtain solvent-free loaded implants. The interaction phenomena involved in the supercritical impregnation were studied by following in situ scCO sorption within the polymer support and the subsequent IOL swelling, and by taking into account drug solubility in the supercritical fluid phase. The drug impregnation yields determined though in-vitro release studies varied between 0.33 and 1.07 ± 0.07 μg·mg in the studied experimental conditions (8 to 25 MPa, 308 to 328 K and 30 to 240 min impregnation duration). An impregnation duration longer or equal to the time required for a complete CO uptake by the polymer as well as a higher pressure or a higher temperature over the crossover pressure delimiting the upper limit of the retrograde solubility zone, led to higher drug impregnation yields.