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Chemotherapy Drugs, Cytotoxic Drugs

What is Chemotherapy

Administration of cytotoxic drugs (chemotherapy drugs) which will act on abnormal cells as well as cancer cells.  What is cancer, Cancer is defined as abnormal growth of the cell which is function-less, limitless, purposeless and it has tendency to penetrate in other surrounding tissues.

Cancer is the abnormal, uncontrolled, proliferation growth of the cell. Chemotherapy refers to certain  drugs, which can be inhibited growth or killed cancer cells.  Chemotherapy drugs can be given in the form of injections or oral medications. Majority of chemotherapy drugs are administered through intravenous route.

Some other routes, chemotherapy agents can be given….

  •  Intramuscular
  •  Subcutaneous
  •  Intrathecal
  • Intravenous
  • Oral

Chemotherapy usually administer in cycle, respectively every few weeks.

There are some basic principles of chemotherapy, which we have to follow before administering chemotherapy drugs or agents

Basic Principles

Dose Intensity

Dose intensity is to be maintained by giving drugs as constant intervals.


In cancer primary line of treatment is chemotherapy and secondary is the radiation therapy, then surgery. In this therapy, chemotherapy is to be given before the surgery.


Here primary line of treatment is surgery or radiation therapy and then secondary is chemotherapy drugs. In this type, chemotherapy is to be given after surgery.

Combination of Chemotherapy

In this type, two treatments are given together. Chemotherapy and radiation therapy given simultaneously in combination, because some tumors are very sensitive to radiation.

Single Agent Chemotherapy

Name itself suggest the meaning. In this type, only one chemotherapy drug is given to the person.

Tumor Growth

Chemotherapy acts on the cells of the tumor as per the growth. If the higher growth of tumor, more cells would be killed.

Highest Proliferation

Chemotherapy drugs acts on more cells, which are abnormal. If the proliferation rate of the tumor is high then more cells would be dead.

Small Vascular Tumor

Chemotherapy works as per vascular supply of that area.  Suppose small tumor are getting good vascular supply.  The response which get from chemotherapy is positive and very quickly.

Less Proliferation and Blood Supply

It is exact opposite to above principle, when tumor having less supply of blood and proliferation, then chemotherapy slowly. It gives slowly response in such person.

Molecular Targeted Therapy

Molecular targeted therapy specially targets a known critical molecular pathway of tumor growth.  It acts on the targeted cells and killed them. If targeted therapy is used with the combination of chemotherapy then it gives good result or response.


Sometimes cancer cells are resist to chemotherapy drug. Some cancer cells has ability to mutate spontaneously and some are resistant to treatment.