Oxidation causes cataract formation in human and hydrogen peroxide (H2O2), present in aqueous humor, rises 5-10 fold and is cytotoxic in cataract patients. Lens has a high concentration of glutathione (GSH) which can detoxify the oxidants, but GSH decreases with age and development of cataract. Calcium channel blockers such as nifedipine and nicardipine display antioxidant activity. Therefore, we compared the effects of GSH with nifedipine and nicardipine on H2O2-induced oxidation of bovine lens epithelial cells (BLEC). BLEC were cultured in a humidified atmosphere of 5 % CO2, at 37 degrees C. For determination of IC50, 100, 200, 300 or 500 mu M H2O2 were applied for 3 hours. Simultaneously 200 mu M H2O2 either with GSH, nicardipine (1, 3 mu M) or nifedipine (1, 3 mu M) were added to the culture medium for 3 hours, removed and refed for 24 hours. After 27 hours, drug cytotoxicity was determined by using a colorimetric assay. H2O2 at 200 mu M induced approximately 50 % cell death (p<0.001) and 1000 mu M GSH was protective against H2O2 toxicity. GSH increased cell viability by 25 % (p<0.001), but nifedipine and nicardipine did not prevent H2O2-caused death. When applied simultaneously with H2O2, GSH has a strong antioxidant effect however, nicardipine and nifedipine can not block the oxidation.