A variety of chemotherapy drugs are available for the treatment of different cancers. The drugs can be administered orally, into a vein, under the skin or into the muscle. Depending on the type of cancer being treated, a combination of categories of chemotherapy drugs may be administered. Chemotherapy drugs are divided into groups based on what they target and their chemical structure. Different groups of drugs result in different complications, while they all tend to result in nausea. There are four major categories of chemotherapy drugs.
Alkylating Agents
Alkylating agents are the most commonly used chemotherapy drugs available. These agents directly attack the DNA strand of the cancer cell in an attempt to prevent the cell from replicating. Alkylating agents work during all phases of the cell cycle. These drugs are used for most types of cancer, but are usually most effective in treating slow-growing cancers, according to the National Cancer Institute. Because alkylating agents attack DNA, complications include bone marrow damage, which can lead to the development of leukemia. This risk increases 5 to 10 years after treatment, according to the American Cancer Society.
Antimetabolites
Antimetabolites have a structure similar to that of vitamins and amino acids and work by interfering with DNA and RNA growth. These drugs imitate nutrients that the cancer cells need to grow. The cancer cell will consume the antimetabolites, which will then work to starve the cell. Antimetabolites are phase specific and work only during the S phase of the cell cycle, which is when cells are replicating their DNA strands. This class of drugs is used most often to treat gastrointestinal tract, ovary and breast cancers, according to Mesothelioma Web.
Anti-Tumor Antibiotics
Anti-tumor antibiotics work by forming free radicals that break DNA strands. The free radicals produced bind with DNA, causing it to uncoil and also prevent RNA synthesis. Without RNA synthesis, the cancer cells cannot make proteins, which are crucial for cell survival, according to the National Cancer Institute. Anti-tumor antibiotics work during all phases of the cell cycle, and thus are prescribed for a variety of cancers. Complications associated with these drugs are the development of leukemia and permanent heart damage. Because of these risks, lifetime intake limits are usually placed on anti-tumor antibiotics.
Plant Alkaloids
Plant alkaloids are chemotherapy drugs made from plants. They work by blocking cell division and preventing the cancer cell from becoming two separate cells. Plant alkaloids are further divided into four separate groups: topoisomerase inhibitors, vinca alkaloids, taxanes and epipodophyllotoxins, according to Mesothelioma Web. Plant alkaloids are cell-cycle specific, however, the phase during which the drug is most effective depends on which category of plant alkaloid is being administered.
