Chemotherapy and Antibiotics - Essay Example

Chemotherapy and Antibiotics Introduction Cancer is the abnormal production of the cells of an organism which are proliferated in an uncontrolled way and sometimes spread. Cancer is commonly used for all types of malignant tumors, which is the swelling of any tissue of the body caused by inflammation, which are studied in Oncology. Neoplasm is defined by a British oncologist Willis as “Abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of the normal tissue and persists in the same excessive manner after cessation of the stimuli which evoked the change.”(Willis 5). The types of cancer are more than 100 because there are more than 100 different types of cells in the body of an organism, for example skin cancer, lungs cancer, prostate cancer and breast cancer etc (Robbins et al 2003). Under microscope, cancer cells show different structural characteristics because of which they can be differentiated from the normal cells. They are pleomorphic in nature, which means that they have a tendency to have a variable size and shape than the normal cells. The cancer cells have different size and different shapes. Most of the cancer cells have large nuclei from the surrounding normal tissue cells and the nuclei of the cancerous cells contain abnormal number of chromosomes, a condition known as aneuploidy. The aneuploidy may occur due to mutation or deletion of chromosome or any other reason. The brief introduction about cancer helps in the development of anticancer drugs. Chemotherapy is the solution to the development of cancer and in order to carry out chemotherapy certain drugs have to be administered (Rousseau 2007). Anti-Cancer Drugs Currently the anticancer drugs being used are alkylating agents, Antimetabolites, Purine Antagonists, Pyrimidine Antagonists, Plant Alkaloids and Antibiotics. The primary class of anticancer drugs which would be emphasized in this essay are Antibiotics or antineoplastic drugs. Antibiotics used in cancer are formed from agents such as doxorubicin, daunorubicin, dactinomycin and mitomycin. All these drugs would be described further which are being widely used in the chemotherapy of cancer (Katzung 2004; Finkel et al 2009; Rousseau 2007) Antibiotics and Chemotherapy Doxorubicin and Daunorubicin Doxorubicin and Daunorubicin are anthracycline antibiotics which originate from Streptomyces peucetius var caesius. They are the most used cytotoxic cancer drugs these days. Mechanism of Action:- These antibiotics act on the base pairs inhibiting the enzyme topoisomerase II. Thus acting on the base pairs helps in the inhibition of RNA and DNA. They also act on the cell membranes to alter or stop the ion transport which would then cause a change in the fluidity of the cell. It also generates free radicals by reduction through enzymes. These antibiotics are also related to cardiac toxicity because of the production of free radicals. Pharmokinetics:- These drugs are given intravenously to patients and are hydrolyzed in the liver. It forms a hydroxylated metabolite which is active in nature and an aglycone which is inactive. Most of the constituents of the drugs are excreted through bile secretion of the liver. Clinical Use:- Doxorubicin is widely used as an anticancer drug in breast cancers, urogenital system cancers, thyroid, stomach and lung cancers. It is also used in Hodgkin’s and non-Hodgkin’s lymphomas. Doxorubicin is usually used with other anticancer reagents which improves the results. Daunorubicin on the other hand can only be used for acute myeloid lymphomas. It does not prove to be much effective in solid tumors. Side Effects:- The most common side effect of these drugs is that it can cause cardiac toxicity thus resulting in arrhythmias of the heart. It can also cause the bone marrow to reduce its activity. Cardiac toxicity generated by these drugs can be inhibited by administering an inhibitor such as Dexrazoxane (Katzung 2004; Finkel et al 2009). Mitoxantrone Mechanism of Action:- It is an anthracene drug which is an important chemotherapic drug used in leukaemia. It acts on the DNA strand to inhibit both RNA and DNA synthesis. Pharmokinetics:- The drug can remain in the plasma for a long duration of 75 hours and most of it is excreted through the biliary duct. Clinical Use:- It is mostly recommended in patients suffering from prostrate cancer, non Hodgkin’s lymphoma and breast cancer. Side Effects:- It causes nausea, vomiting, inflammation of the mucosa and cardiac toxicity. It is less toxic than Daunorubicin and Doxorubicin (Katzung 2004; Finkel et al 2009). Dactinomycin Mechanism:- It is a drug which originates from streptomyces organism. It acts on the base pairs of DNA to inhibit RNA synthesis. It primarily acts on the guanine-cytosine pairs of the DNA and the most affected RNA is messenger RNA as it is the one most dependent on DNA. Pharmokinetics:- It is given parenterally and is excreted via bile through the liver. Clinical Use:- It is widely used in the tumours which develop in the children. Wilm’s tumor and melanoma are examples of tumours in which it can be used. Toxicity:- It causes the suppression of bone marrow activity, and irritation in the gastrointestinal tract (Katzung 2004; Finkel et al 2009). Mitomycin Mechanism of Action:- The drug origantes from Streptomyces caespitosus. It is an agent which gets activated after being reduced. This activated agent then acts on the DNA strand to stop its function. Pharmokinetics:- It is cleared from the blood through hepatic metabolism. Clinical Use:- It best acts with radiation therapy in order to attack hypoxic tumour cells. The solid tumours are affected by this antibiotic. The squamous cell cancers in anus can be rapidly cured by the administration of Mitomycin and fluorouracil. It can also be used in the carcinomas of stomach, cervix, and lungs. Side Effects:- This antibiotic like other antibiotics is also toxic to the heart, liver and kidneys. It also causes myelosuppresion (Katzung 2004; Finkel et al 2009). Bleomycin Mechanism of Action:- It is a glycopeptides that has both a DNA binding region and an iron binding region. It acts on the DNA strands causing it to break and hence inhibiting the synthesis of double strands of DNA. It acts by the addition of oxygen and removal of hydrogen from a FeII complex in DNA. It causes the cells to accumulate in the meiotic G2 phase where they cannot further reach their final developmental stage. Pharmokinetics:- It is administered parenterally and is removed by the activation of aminopeptidases. Some of the drug is also excreted through the action of kidneys. Clinical Use:- It is used to treat several of lymphomas like Hodgkins lymphoma and cancer of the testis. It can also help to treat the squamous cell cancers. Side Effects:- It is toxic in nature as it has a negative effect on lungs and can cause allergic reactions. It can cause pulmonary fibrosis and anaphylaxis (Katzung 2004; Finkel et al 2009). Conclusion All these above mentioned drugs have an important role to play in the eradication of cancer from the body. Chemotherapy acts by increasing the log kill of the cancer cells hence increasing the death rate of the cancer cells. Through chemotherapy both the resting and developing cells are targeted. The toxic effects of the drugs used in cancer can be lessened with the help of a rescue strategy. This rescue strategy aims to lower the dozes of the drugs given. Other drugs can also be given such as Leucovorin which plays a primary role in decreasing the effects of toxicity. Chemotherapy is an important process through which cancer can be minimized and it is through this process that many remarkable achievements have been done to cure it. However the different types of cancers are still not completely curable and a better option may still be looked upon by the researchers to cure the increasing forms of cancer. Many of the scientists are now relying on the new stem cell research to solve the mysteries of cancer (Katzung 2004; Rousseau 2007). References Willis, Rupert Allan. The Spread of Tumors in the Human Body. London: Butterworths, 1952. Kumar, Vinay, Ramzi S. Cotran, and Stanley L. Robbins.Robbins Basic Pathology. Philadelphia, PA: Saunders, 2003. Top of Form Katzung, B. G. (2004). Basic & clinical pharmacology. New York: Lange Medical Books/McGraw Hill. Bottom of Form Top of Form Finkel, R., Clark, M. A., Cubeddu, L. X., Cooper, M., Flatt, C. T., & OLeary, L. (2009). Pharmacology: Lippincotts illustrated reviews. Philadelphia [etc.: Lippincott Williams & Wilkins. Top of Form Rousseau, P. (January 01, 2007). Chemotherapy. Jama : the Journal of the American Medical Association, 298, 6, 604. Bottom of Form Bottom of Form Read More