Antineoplastic agents By Dr Abdul Samad Salahuddin - PowerPoint Presentation

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Antineoplastic agents

By Dr Abdul Samad Salahuddin

Antineoplastic agentsAntineoplastic agents are drugs used for the treatment of cancer, malignancy, tumor, carcinoma, sarcoma, Leukemia, or neoplasm (Greek neo = new, Plasm = formation). Neoplasm refers to a group of diseases caused by several agents, namely, chemical compounds and radiant energy. Cancer is characterized by an abnormal and uncontrolled, division of cells, which produces

tumours and invades adjacent normal tissues. Often, cancer cells separate themselves from the primary tumour, and are carried by the lymphatic system to reach distant sites of the organs, where they divide and form secondary tumors (metastasis).Not all tumors are cancerous, Benign Tumors do not Invade neighboring tissues and do not metastasize.

Limitations of TherapyCancer cells very rapidly develop resistance to antineoplastic drugs.Differences between normal and neoplastic human cells are merely quantitative.Biochemical and morphological differences between normal and neoplastic cells are slight; therefore:

antineoplastic agents are devoid of selective toxicity to tumor cells.Antineoplastic agents kill cells by first-order kinetics, that is, they kill a constant fraction of cells.However, some of the cancer cells elude killing and one of these cells may restablize the tumour. It is extremely difficult to kill all the malignant cells.Most antineoplastic drugs are highly toxic to the patients.

Classification:Antineoplastic agents are classified as follows:I. Alkylating agentsII. AntimetabolitesIII. AntibioticsIV. Plant products

V. EnzymesVI. HormonesVII. Immuno therapyVIII. Monoclonal antibodies

IX. Radio-therapeutic agentsX. Cyto-protective agentsXI. Miscellaneous.

III. Plant Alkaloidsa. Vinca Alkaloids

Trastuzumab

CisplatinCarboplatin

Mechanism of Action of Alkylating agentsAlkylating agents involve reactions with guanine in DNA. These drugs add methyl or other alkyl groups onto molecules where they do not belong. This in turn inhibits their correct utilization by base pairing and causes a miscoding of DNA.In the first mechanism an alkylating agent

attaches alkyl groups to DNA bases. This alteration results in the DNA being fragmented by repair enzymes in their attempts to replace the alkylated bases.A second mechanism by which alkylating agents cause DNA damage is the formation of cross-bridges, bonds between atoms in the DNA. In this process, two bases are linked together by an alkylating agent that has two DNA binding sites. Cross-linking prevents DNA from being separated for synthesis or transcription.

Example

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