Cancer and cancer treatment drugs are many. These drugs are divided into a number of groups depending upon nature and use of these drugs. Basically they are divided into 6 groups namely: antimetabolites, anthracyclines, alkylating agents, plant alkaloids, antitumour agents and finally topoisomerase inhibitors. The administration of these drugs affects the cells directly i.e. they affect the division of the DNA function. These drugs have antibodies which are singular in structure and have found to cause abnormality in certain kinds of cancer such as gastro intestinal cancers and in myelogenous leukemia.
Alkylating agents are important and are aptly named as they have shown to add up alkyl groups to some cells that have electronegative groups. Carboplatin when combined with oxaliplatin and cisplatin become alkylating agents. Some of the other alkylating agents are mechlorethamine, chkirambucil and cyclophosphamide. These agents help in modifying DNA cells.
Other than alkylating agents anti-metabolites also help in the building up of DNA cells and are known as block builders. They prevent normal division of DNA cells, due to this synthesis of the RNA is greatly affected
Plant alkaloids are plant extracts and they too help in preventing cell division. This is an important feature and some examples are Vinca alkaloids and Taxannes. The name vinca alkaloids come from Catharanthus roseus and Madagascar periwinkle whose extracts have been found to help treat leukemia. The other plant alkaloids are Vindesine, Vinorelbine, Vinblastine and Vincristines.
Another plant alkaloid is Podophyllotoxin and two other drugs produced from it are etoposide and teniposide. The Himalayan May Apple is supposed to have a large quantity of the above mentioned compounds. This is an endangered plant species.
Drug taxannes if derived from paclitaxel and is a plant extracted from Yew tree bark. It is used to prevent chromosome separation and gives strength to the microtubules.
The most essential enzyme which obstructs the duplication of DNA cells is the Topoisomerase inhibitors. Many anti tumor drugs or antibiotics are available today. Dactinomycin is used during kidney transplantation.
There are many more agents that work against destroying the tumor in the body without being directly involved in the process of blocking the newer tumors to grow. These are known as monoclonal antibody. Some examples of monoclonal antibodies are trastuzumb or Herceptin, Bevacizumab or Avastin, cetuximab, rituximab or Rituxan or Mabthera.
Due to chemotherapy the regeneration of new cells is greatly affected, Hodgkin's disease, myelogenous leukemia etc are sensitive to this mode of treatment and the growth rate slows down due this chemotherapy. Though due to chemotherapy many healthy cells are also destroyed, but then you can always use other therapies to solve your problem as you can make use of the number of combination drugs available while you undergo chemotherapy.
On the whole almost all chemotherapy agents' main purpose is to destroy cancer cells that affect the proper functioning of the DNA through various drug cycles. Some side effects are commonly seen in almost all the modes of treatments, there are some side effects that ware off after the completion of the cycle but some leave a permanent damage.