Lactate dehydrogenase (LDH) is an oxidoreductase which catalyzes the interconversion of lactate and pyruvate. Cytotoxic compounds often compromise cell membrane integrity by inducing apoptosis or necrosis. LDH is a stable cytosolic enzyme that upon membrane damage is released into the cellular environment. Therefore, LDH is often measured to evaluate the presence of tissue or cell damage. The colorimetric LDH release assay is a simple and robust Method to assess cytotoxic effects on cells by measuring the activity of LDH in cell culture supernatant. The assay is based on the reduction of a tetrazolium salt to a formazan dye.