Antimetabolites

Antimetabolites are structural analogues of naturally occurring compounds and function as fraudulent substances for vital biochemical reactions. Folic Acid Analogues Methotrexate (Amethopterin) is a folic acid antagonist that binds to dihydrofolate reductase, thus interfering with the synthesis of the active cofactor tetrahydrofolic acid, which is necessary for the synthesis of thymidylate, purine nucleotides, and the amino acids serine and methionine. Methotrexate is used for the following types of cancer: • Acute lymphoid leukemia: During the initial phase, vincristine and prednisone are used. Methotrexate and mercaptopurine are used for maintenance therapy. In addition, methotrexate is given intrathecally, with or without radiotherapy, to prevent meningeal leukemia. • Diffuse histiocytic lymphoma: Cyclophosphamide, vincristine, methotrexate, and cytarabine (COMA). • Mycosis fungoides: Methotrexate. • Squamous cell, large-cell anaplastic, and adenocarcinoma: Doxorubicin and cyclophosphamide, or methotrexate. • Head and neck squamous cell: Qi-platinum and bleomycin, or methotrexate. • Choriocarcinoma: Methotrexate. Tumor cells acquire resistance to methotrexate as the result of several Read more […]

ANTICANCER AGENTS

ANTICANCER AGENTS are commonly referred to as antineoplastic agents, however, by strict definition, antineoplastic agents are used to treat a neoplasm’ (meaning a ‘new growth’). Neoplasms that have only the characteristic of localized growth are classified as benign. Neoplasms with the additional characteristic of invasiveness, and/or the capacity to metastasise, are classified as malignant. The term cancer’ is usually applied only to the latter group. Similarly, the word tumour (meaning literally ‘a local swelling’) tends to be used in association with cancer, and antineoplastic agent’ is commonly interchangeable with ‘anticancer’. There are a number of approaches to the chemotherapy of cancer, and most can be regarded as complementary or additional to radiotherapy and surgery. Direct approaches to cancer mostly use cytotoxic agents: these work by interfering with cell replication or production, so preventing the growth of new cancerous tissue. Inevitably, this means that normal cell production is also affected, causing serious side-effects. There are many cytotoxic agents with diverse modes of action, but these can be divided into groups on the basis of their mechanisms of action. Alkylating agents and related Read more […]