In vitro evaluation of bleomycin-induced cell lethality from plastic and glass containers. To optimize cancer chemotherapy, a considerable amount of research has been expended to study pharmacologic, pharmacokinetic, biochemical, and pharmaceutic properties of antineoplastic agents. However, published data on the stability and compatibility of these agents in various administration fluids and containers are few in number. Evidence of a significant decrease in stability as shown by high-performance liquid chromatography has been reported when bleomycin was infused in plastic containers for prolonged periods (over 24 hours) as compared with the same procedure with glass containers. Because administration of bleomycin is usually given as a continuous infusion, we undertook this study to determine whether the drug loss of stability that occurs in plastic containers results in a therapeutic loss of efficacy (cytotoxicity). By using a tumor stem-cell assay we compared the quantitative effects of bleomycin in plastic and glass containers on cell lethality. The results from our assay showed no significant difference in cell lethality by bleomycin from its aqueous solution stored in glass and plastic containers over the time periods observed. If these results had been statistically significant, the tumor stem-cell assay may have been shown to be a more sensitive means of determining the clinical significance of these stability studies. 