LOSS OF IN-VITRO CYTOTOXICITY OF CISPLATIN AFTER STORAGE AS STOCK SOLUTION IN CELL-CULTURE MEDIUM AT VARIOUS TEMPERATURES

BACKGROUND. Cisplatin (cis-dichlorodiammineplatinum [II]) is one of th e most potent and widely used cytotoxic drugs in cancer therapy. Howev er, in vitro cytotoxicity assays often yield diverging results. Theref ore, it is believed by many investigators that cisplatin is not effect ive in vitro. The authors investigated whether the experimental condit ions used could be responsible for the diverging results. METHODS, In vitro cytotoxicity assays were performed using the original cisplatin solution as distributed by the manufacturer or a 5-fold dilution of th is in cell culture medium after storage for 2 weeks or 1 month at Vari ous temperatures (room temperature, 4 degrees C, and -20 degrees C). R ESULTS. The original solution of cisplatin retained the full cytotoxic potency for at least 1 month under all storage conditions tested. The highest loss of cytotoxicity resulted from storage of cisplatin in ce ll culture medium in which a >7-fold increase in the concentration tha t inhibits 50% occurred after 2 weeks' storage at room temperature. So lutions stored in culture medium at -20 degrees C retained full cytoto xic potency. CONCLUSIONS, Cisplatin is a potent cytotoxic drug in vitr o when stored under appropriate conditions. These findings are of rele vance for in vitro studies with cisplatin. (C) 1997 American Cancer So ciety.