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Background: Benzalkonium chloride (BAK), the most commonly used preservative in anti-glaucoma eye drops, inflicts damage to the ocular surface. A novel anti-glaucoma formulation that avoids the use of BAK has been developed. The aim of this study was to evaluate the cytotoxicity of this formulation and to compare it with an ophthalmic solution containing BAK. Methods: Two different latanoprost eye drops were used: one ophthalmic solution (LSc) containing BAK 0.02% and one ophthalmic nanoemulsion (LNe) with a soft preservative (potassium sorbate 0.18%). Human epithelial conjunctival cells were incubated for 15, 30, and 60 min with either LSc or LNe. The cytotoxicity was determined by MTT assay. Cell death was measured by flow cytometry using annexin V–FITC and propidium iodide. Results: The values of cell viability and proliferation obtained from cells exposed to LNe were between 80 and 90% relative to the control group, whereas values obtained from cells exposed to LSc were around 30% at all study times (p < 0.05 at 15 and 30 min; p < 0.01 at 60 min). The percentage of viable cells decreased significantly when cells were incubated with LSc compared with cells incubated with LNe at all the study times, while the percentage of cells in late apoptosis/necrosis increased significantly in cells exposed to LSc compared to LNe. Conclusions: The new latanoprost nanoemulsion is significantly less cytotoxic on human conjunctival cells than LSc. These results suggest that the new formulation might be gentler on the eye surface than currently available BAK-preserved latanoprost solutions. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the cytotoxicity of a new Latanoprost Benzalkonium chloride (BAK)‐free nanoemulsion and to compare it with a Latanoprost solution containing BAK. Methods: Normal Human Conjunctival epithelial cells (IOBA‐NHC) were incubated for 15, 30, and 60 minutes with 1:6 dilutions of either latanoprost solution containing BAK (LSc), (latanoprost 0.005%, BAK 0.02%, Xalatan, Pfizer) or latanoprost nanoemulsion (LNe), (latanoprost 0.005%, potassium sorbate 0.18%; Louten Emulsion, POEN). Cytotoxicity was determined by MTT assay. Cell death was measured by flow cytometry using annexin V‐FITC and propidium iodide. Results: Cytotoxicity evaluation: the values of cell viability and proliferation obtained from cells exposed to LNe were between 80 and 90% relative to control group, whereas values obtained from cells exposed to LSc were around 30% relative to control group at all study times (p < 0.05 at 15 and 30 minutes; p < 0.01 at 60 minutes). Cell death evaluation: the percentage of viability was significantly lower in cells exposed to LSc compared with those incubated with LNe at all study times (p < 0.05 at 15 and 30 minutes; p < 0.01 at 60 minutes). Viability of cells exposed to LNe was higher than 90% at all study times, whereas there was a time‐dependent decrease in cells exposed to Lsc. The percentage of viable cells in the LNe group was comparable to the viability of control group (93.1%) at all study times. No statistical differences between groups reached in early apoptotic cells. A significant increase of late apoptosis and necrosis cells were observed at all study times for those incubated with Lsc (p < 0.05; p < 0.01 at 30 and 60 minutes). Conclusions: The new latanoprost nanoemulsion is significantly less cytotoxic on human conjunctival cells than LSc. It suggests that the new formulation could be gentler on the eye surface than currently available BAK preserved latanoprost solutions, with levels of cytotoxicity equivalent to control. [ABSTRACT FROM AUTHOR]