Cytotoxic refers to a substance or method which ends in cell harm or necrobiosis. The prefix "cyto" refers to cell and "toxic" to poison. The term is usually wont to describe therapy medication that kill cancer cells, however it should even be wont to describe toxins, like venom.Cytotoxicity is that the quality of being cytotoxic to cells. Samples of cytotoxic agents area unit Associate in Nursing immune cell or some forms of venom, e.g. from the puff adder (Bitis arietans) or brown recluse spider (Loxosceles reclusa). Toxicity assays area unit wide utilized by the pharmaceutical trade to screen for toxicity in compound libraries. Researchers will either hunt for cytotoxic compounds, if they're fascinated by developing a therapeutic that targets speedily dividing cancer cells, for instance; or they will screen "hits" from initial high-throughput drug screens for unwanted cytotoxic effects before finance in their development as a pharmaceutical. Cytotoxic to cells, cell-toxic, cell-killing. Any agent or method that kills cells.