Cytotoxicity: definition, agents, effects and precautions

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Cytotoxicity refers to a substance or process that causes cell damage or death. The prefix "cyto" refers to a cell and "toxic" refers to a poison. The term is often used to describe chemotherapy drugs that kill cancer cells, but it can also be used to describe toxins such as poison. Our own immune system contains cells that are considered cytotoxic, such as T cells, which kill bacteria, viruses, and cancer cells. The "cytotoxic" label is important to healthcare professionals who will be working with cytotoxic drugs or other substances. which can cause cell death, and special precautions are needed to ensure safety. Cytotoxicity tests are important for safety, from environmental exposures to medical devices .

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Cytotoxic drugs

In most cases, the term "cytotoxic" refers to the effect that a chemotherapy drug has on cancer cells . In this sense, a cytotoxic agent can be distinguished from a cytostatic agent. Cytostatic drugs, on the other hand, suppress cell growth and division, but do not directly lead to cell death .

Cytotoxic drugs work by disrupting cells at specific places in the growth cycle. They are more likely to infect fast-growing cells such as cancer cells, hair follicles, bone marrow, and cells that line the stomach and intestines. The reason that most chemotherapy regimens involve a combination of drugs ( combination chemotherapy ) and that most chemotherapy cycles are repeated is because the cells are in different places during the division process.

Not all drugs used to treat cancer are cytotoxic. Chemotherapy drugs are designed to kill all fast-growing cells, including normal cells that divide rapidly. Some of the newer types of cancer drugs, such as targeted therapy and immunotherapy, are not considered cytotoxic. These drugs work by targeting a specific growth pathway for cancer cells or by stimulating or using the immune system to fight cancer. Certain immunotherapies, such as CAR T, can be considered cytotoxic in a sense because they exploit the cytotoxic effect of the body's own cytotoxic T cells.

Cytotoxic agents in humans or animals.

There are other cytotoxic substances that are used for a variety of functions. As with cytotoxic chemotherapy drugs, this simply means that they kill cells.

Cytotoxic T cells

Cytotoxic agents are not only designed to kill cancer and fight disease. Our body also produces cytotoxic T cells (cytotoxic T lymphocytes). Cytotoxic T cells (CD8 + cells and natural killer lymphocytes) are part of the immune system that seeks out, finds, and destroys virus-infected cells and cancer cells.

One of the fastest growing areas of cancer research is currently focused on using and stimulating our own cytotoxic cells to fight cancer in our bodies. These treatments work in different ways; some allow T cells to "see" previously hidden cancer cells, others by collecting and multiplying these cells, and much more.

Cytotoxic poison

It's not just humans that use cytotoxic T cells. Some poisons, such as those secreted by vipers, cobras, and triple spiders, are also cytotoxic.

Mechanism of action

Cytotoxic agents can kill cells in a number of ways. They can damage the cell, so that its cell membrane weakens and the cell explodes (lysis), or they can interfere with cell division, so that the cell stops growing and dividing .

The terminology can be confusing when considering drugs or other substances that damage cells or cell DNA.

Cytotoxic versus genotoxic

There is much confusion between the terms cytotoxic and genotoxic. The term cytotoxic refers to the ability of a substance to damage cells. The term "genotoxicity" refers to the ability of a substance to directly damage DNA in cells. When DNA is damaged, it may or may not die. In fact, the resistance of cells that carry damaged DNA (mutations) that cannot be repaired is the basis of cancer development. Cancer is often the result of a series of mutations of oncogenes (genes that code for proteins that stimulate cell growth) and tumor suppressor genes (genes that code for proteins that repair damaged DNA or cause cell death if the DNA is not reactivated). can repair). ). BRCA genes are examples of tumor suppressor genes.

Carcinogenicity / mutagenicity

When talking about cytotoxicity, it is important to explain a few more definitions. The term carcinogen refers to a cytotoxic substance that has the ability to cause DNA damage that can ultimately lead to cancer. In contrast , the term "mutagen" refers to cytotoxic substances that could potentially damage the chromosomes or genes of the fetus.

This is why it is extremely important to be careful when handling drugs and cytotoxic substances.

Dangers of Cytotoxic Drugs and Agents

Cytotoxic drugs can kill cancer cells, but they can also damage normal, healthy cells, as demonstrated by the side effects of most chemotherapy drugs.

Cytotoxic precautions

Those working with cytotoxic drugs or other substances are advised to take special precautions to avoid carcinogenicity and mutagenicity. Specific precautions can vary significantly depending on the route of exposure, but can include :

  • Gloves with cuffs tucked under the gloves
  • Long sleeves
  • Disposable gowns
  • Safety glasses
  • Respiratory protection

With some cancers, patients may need to take cytotoxic precautions when they return home. These include measures to protect other family members who may be unintentionally exposed to bodily fluids that contain cytotoxic chemicals.

Cytotoxicity test

Cytotoxicity tests are used in the development of many products, from drugs to cosmetics. Herbal products (for use in extracts, etc.) Pass toxicity tests. The term called "selectivity index" describes the relationship between the potential biological activity in a plant sample and its potential cytotoxicity.

Get the word of drug information

The term "cytotoxic" can be intimidating, especially if you see a label on what will be injected into your body. But our own body also produces cytotoxic substances. However, it is important to understand how these substances work to protect yourself from the environment.

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