Cytotoxicity refers to the capacity of a substance or agent to cause damage or death to living cells, reflecting a critical parameter in pharmacology, toxicology, and biomedicine. It is distinct from cytostatic effects, which inhibit cell growth and proliferation without causing cell death. Cytotoxic agents can induce a range of cellular responses, including inhibition of cell growth, induction of apoptotic or necrotic cell death, and disruption of metabolic or structural cellular integrity. Assessing cytotoxicity is fundamental for evaluating the safety and efficacy of pharmaceutical compounds, chemicals, and biomaterials, as it helps predict potential adverse effects and guides therapeutic development.
Various assays—based on enzyme activity, membrane permeability, metabolic activity, or cell proliferation—are routinely employed to characterize and quantify cytotoxic effects in vitro, providing essential insights into cell viability and the mechanisms underlying toxic responses.