What kinds of drugs are used in chemotherapy?
There are several groups of chemotherapy drugs that are categorized on when and how they affect cancer, but I am just going to write a bit a few. the first drug i am going to talk about is the Alkylating Agents. Alkylating agents directly damage the DNA in a cell and stop the cell from reproducing. These kinds of drugs are not phase specific so they can attack cancer in any period of it's life. Alkylating agents are used to treat leukemias, lymphomas, Hodgkin Disease, myeloma, sarcoma and other cancers including breast, lung and ovary. Since these drugs damage DNA, this could lead to various side effects that include, but are not limited to, bone marrow damage and acute leukemia. Getting leukemia from using this drug is "dose-dependent" which means that the more you take, the higher the chances of leukemia appearing. The highest risk to get leukemia when using alkylating agent treatment is during 5-10 years after first starting treatment. Some examples of alkylating agents are nitrogen
mustard, nitrosoureas, alkyl sulfonates, triazines, ethylenimines, etc.
The next group of drugs are called Antimetabolites. These drugs target the cells during the S phase, where the DNA is replicated. Anitmetabolites substitute normal building blocks of DNA and RNA with something else. Antimetabolites are used to treat leukemia, cancers in the ovary, breast, intestinal tract and other cancer. Examples of antimetabolites are 5-fluorouracil (5-FU), 6-mercaptopurine (6-MP) , Capecitabine (Xeloda®), Cladribine, Clofarabine ,Cytarabine (Ara-C®), Floxuridine ,Fludarabine, Gemcitabine (Gemzar®), Hydroxyurea, Methotrexate, Pemetrexed (Alimta®), Pentostatin, Thioguanine, etc. Anti-tumour Antibiotics are drugs that interfere with the enzymes involved with DNA replication. This group of drugs also works in any stage of the cell cycle. When giving this drug at high doses, there is a chance to permanently damage the heart. This is the reason why that the labels on the drugs have a lifetime dosage amount on them. These drugs are used for a variety of cancers. Examples of anti-tumour anitbiotics include Daunorubicin, Epirubicin, and Idarubicin. The last groups of drugs I am going to talk about are Topiosomerase Inhibitors and Miotic Inhibitors. Topoisomerase inhibitors are seperated into 2 sub-groups, Topoisomerase I and Topoisomerase II. These drugs interfere with enzyme that help seperate strands of DNA that are to be copied, called topoisomerases. Topoisomerase inhibitors can be used to treat lung cancer, breast cancer, other kinds of cancers, and certain leukemias, but by using Topoisomerase II, you will have a higher chance of acquiring acute myelogenous leukemia within 2-3 years of treatment. Examples of topoisomerase I include topotecan and irinotecan (CPT-11) and examples of topoisomerase II include etoposide (VP-16) and Mitoxantrone (which is an anti-cancer antibiotic which is very similar to topoisomerases. Miotic inhibitors affect cancer during mitosis or they interfere with the production of proteins needed for cellular reproduction. They are often natural products or plant alkaloids. These drugs affect cancer during the M phase, cut can also damage cells in all the other stages. This can cause peripheral nerve damage and are used to treat many different types of cancer. Examples of Miotic inhibitors include (paclitaxel, docetaxel, ixabepilone, vinblastine, vincristine, etc.) There are also targeted therapies that are currently being developed to attack specific cells and there are also differentiating agents which help the cancer cells mature into normal cells. Immunotherapy is the stimulation of the immune system to naturally fight the cancer, and hormone therapy is a way to prevent cells from using the needed hormones to reproduce. |