EVALUATION OF CYTOTOXICITY OF VARIOUS OPHTHALMIC DRUGS, EYE DROP EXCIPIENTS AND CYCLODEXTRINS IN AN IMMORTALIZED HUMAN CORNEAL EPITHELIAL-CELL LINE

Purpose. An immortalized human corneal epithelial cell line (HCE) was tested as a screening tool for prediction of topical ocular irritation /toxicity by pharmaceuticals. Methods. Effects of various drugs, excip ients and cyclodextrins (CDs) on viability of HCE cells were evaluated using two in vitro cytotoxicity tests, 3-(4,5-dimethylthiazol-2-yl)-2 ,5-diphenyl tetrazolium bromide (MTT) dye reduction assay and propidiu m iodide assay. Results. Mitochondrion-based MTT test was a more sensi tive indicator of cytotoxicity than the plasma membrane-based propidiu m iodide test. The tests revealed following cytotoxic rankings for oph thalmic drugs: dipivefrin > timolol > pilocarpine approximate to dexam ethasone; for excipients: benzalkonium chloride (BAC) > sodium edetate (NA(2) EDTA) > polyvinyl alcohol (PVA) > methylparaben; and for CDs: alpha-CD > dimethyl-beta-cyclodextrin (DM-P-CD) > sulfobutyl ether P-c yclodextrin ((SBE)(7m)-beta-CD) approximate to hydroxypropyl-beta-cycl odextrin (HP-beta-CD)> gamma-CD. In consideration of the in vivo clini cal situation, the short exposure time (5 min) is more relevant even t hough toxic effects of some test substances were seen only after longe r exposure times (30 and 60 min). Conclusions, Immortalized HCE cells are a promising tool for rapid cytotoxicity assays of ocular medicatio ns. The cell line is potentially useful in predicting the in vivo corn eal toxicity of ocularly applied compounds.