Abstract
Purpose::
Loteprednol etabonate is a prednisolone analog modified to minimize its effect on the lens and trabecular meshwork. However, its effect on retinal cells has not been examined to date. In this study we evaluated the effect of loteprednol etabonate 0.5% suspension on human retinal pigment epithelial cells (ARPE-19) and rat neurosensory retinal cells (R28) in culture.
Methods::
ARPE-19 and R28 cells were grown in tissue culture and treated for 2, 6, or 24 hours with loteprednol etabonate 0.5% suspension (Lotemax, Bausch&Lomb, Tampa, FL) at four concentrations (125, 62.5, 31.25, and 15.62 µg/ml). Cell viability was measured using the trypan blue dye-exclusion assay (ViCellTM analyzer, Beckman Coulter Inc., Fullerton, CA).
Results::
In both cell lines, loteprednol etabonate at 24 hours caused a significant (p<0.01) decrease in cell viability at all concentrations except at the lowest dose (15.62µg/ml) in ARPE-19 cells. The mean cell viabilities at 24 hours of ARPE-19 cells at doses of 125, 62.5, 31.25 and 15.62 µg/ml were 8.2 ± 3.8 %, 80.4 ± 0.9 %, 80.5 ± 1.5 % and 94.4 ± 2.3 % when compared to control untreated ARPE-19 cells (normalized to 100% for comparison purposes). For R28 cells, at the same concentrations at 24 hours, the cell viability was 22.3 ± 3.1%, 58.8 ± 4.6%, 69.7 ± 8.6%, 76.1 ± 6.5% respectively. A toxic effect was seen also at earlier timepoints. At 2 and 6 hours cell viability was decreased in ARPE-19 cells at 125 µg/ml (74.1 ± 0.2 %, 44.4 ± 2.6 % at 2 and 6h, p<0.001), and 62.5µg/ml (88.6 ± 2.5 %, 84.8 ± 3.3 % at 2 and 6h, p<0.01). In R28 cells, at the same time points, loteprednol etabonate was only toxic at a concentration of 125µg/ml (72.9 ± 9.1 %, 54.2 ± 15.4%. for 2h and 6h, p<0.01 and p< 0.001 respectively) At the lowest doses (15.62 and 31.25µg/ml) loteprednol etabonate did not decrease cell viability for either cell line at 2 and 6 hours.
Conclusions::
Loteprednol etabonate was found to be toxic for both retinal pigment epithelial (ARPE-19) and retinal neurosensory (R28) cells in vitro at levels comparable to intravitreal clinical doses (125µg/ml). Based on these experiments, loteprednol does not appear to be a good alternative as a steroid for intraocular treatment.
Keywords: retinal culture • drug toxicity/drug effects • corticosteroids