Currently, several cell-based cytoxicity assays are available for determining cell membrane integrity. Dye uptake assays using neutral red, trypan blue and fluorescent compounds such as propidium iodide are traditional methods to assess cell viability and membrane damage. Trypan blue and fluorescent compounds such as propidium iodide are excluded by healthy, functional cell membranes but are able to traverse damaged cell membranes thereby preferentially staining dead cells. Conversely, neutral red accumulates only in the lysosomes of viable cells. The lactate dehydrogenase (LDH) release assay is widely used in in vitro toxicology studies. This assay is based on the measurement of LDH activity in the extracellular medium. Membrane integrity can be also evaluated by other enzyme release assays including adenylate kinase (Olsson et al., 1983) or glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (Corey et at., 1997), which are present in all cells. These enzymes are normally compartmentalized within the cell, but their activities are significantly increased in the extracellular environment as a result of cell death. However, these assays have their limitations including multiple reagent additions, low sensitivity, low-throughput and scalability, poor linearity, and the need for requisite washes or medium exchanges.