5. CHEMOTHERAPY DRUGS AND THEIR EFFECTS.
Chemotherapy medications fight cancer by attacking cancer cells and preventing their replication, thus stopping tumor growth. There are many different chemotherapy drugs, but most fall into five main classes. These classifications are based on how the chemotherapy works to attack the cancer cell. Each chemotherapy type destroys cancer cells in a different way, but most affect DNA and/or RNA production and replication.
Anti-tumor antibiotics interfere with the production of RNA and DNA, according to the "Core Curriculum of Oncology Nursing." These types of medications produce some of the most severe side effects because the chemotherapy damages many normal cells in the process. Commonly used anti-tumor antibiotics include doxorubicin, epirubicin, daunorubicin, idarubicin, bleomycin, mito-mycin C, mitoxantrone and dactinomycin.
Alkylating agents attack cancer cell by incorrectly linking DNA strands and breaking DNA chains. These medications work throughout cancer cells' life cycle, which makes them useful for many different types of cancer. The American Cancer Society lists mechlorethamine, chlorambucil, cyclophosphamide, ifosfamide, melphalan, streptozocin, carmustine, lomustine, busulfan, dacarbazine, emozolomide, thiotepa and altretamine as commonly used alkylating agents.
Plant alkaloids work by interfering with enzymes, often topoisomerase, which cancer cells need in order to create DNA and divide. Unfortunately, many of these drugs are known for causing irreversible numbness and tingling in the hands and feet. These medications include docetaxel, paclitaxel, vinblastine, vincristine, vinorlbine, ixabepilone, etoposide and estramustine. Two medications that affect topoisomerase but are not plant-based include topetecan and irinotecan.
According to the American Cancer Society, anti-metabolites insert false strands into DNA and RNA during their building phase. This causes irreversible damage to cancer cells, causing them to die. Commonly used anti-metabolites include 5-fluorouracil, capecitabine, 6-mercaptopurine, methotrexate, gemcitabine, cytarabine, fludarabine, floxuridine, cladribine and pemetrexed.
Several of the newer chemotherapy agents are monoclonal antibodies. The first one was approved for cancer treatment by the Food and Drug Administration (FDA) in 1997. Alemtuzumab (Campath), Bevacizumab (Avastin), Cetuximab (Erbitux), Gemtuzumab (Mylotarg), Ibritumomab (Zevalin), Panitumumab (Vectibix), Rituximab (Rituxan), Tositumomab (Bexxar), and Trastuzumab (Herceptin) are some of the FDA-approved monoclonal drugs used in cancer treatments.
Monoclonal antibodies (abbreviated MAbs) are useful in treating colon, lung, head, neck, and breast cancers. Monoclonal drugs are also used to treat chronic lymphocytic leukemia, acute myelogenous leukemia, and non-Hodgkin’s lymphoma.
Monoclonal antibodies work by attaching to certain parts of the tumor-specific antigens and make them easily recognizable to the body’s immune system. Some prevent growth of cancer tumors by blocking the cell receptors to the body’s “growth factors”.
Platinum-based chemotherapy agents work by cross-linking subunits of DNA. These agents act during all parts of the cell cycle and impair DNA synthesis, transcription, and function.
Cisplatin, although found to be useful in treating testicular and lung cancer, is highly toxic and can severely damage the kidneys. Second generation platinum-complex carboplatin are much less toxic in comparison and have fewer kidney-related side effects. Oxaliplatin, which is third generation platinum-based complex, is used to treat colon cancer. Oxaliplatin is