Chemotherapy Drugs 101: Anti-metabolites

Chemotherapy.

The word instills terror, invokes images of hair loss, weakness, sickness. It can be an extraordinarily trying time, for patients and their caregivers. The literally hundreds of different drugs used in chemotherapy treatment can be daunting. In order to try and remove some of the terror and mystery of chemo, I'm going to use this blog to take an occasional look at the various groups of drugs used in chemo—their names, what they are, and what they do—to cancer cells and to our bodies.

In this entry I'll be looking at a couple of the so-called anti-metabolites. These chemotherapy drugs work by pretending to be some of the necessary building blocks of DNA. During the so-called S phase of the cell cycle, they prevent certain actual DNA building blocks from being included. The result is that the cell can't make DNA, it can't grow, and it eventually dies. They are regarded as being very effective, and are therefore used widely in chemotherapy treatment.

The following are some of the primary anti-metabolites used in lymphomas such as Hodgkin's Lymphoma and non-Hodgkin's Lymphoma. Click on the drug to be taken to the American Cancer Society's patient page for that drug, which contains general information as well as potential side effects.

Purine analogues:

Mecaptopurine (marketed as 6-MP and Purinethol).

Thioguanine (marketed as 6-TG, 6-Thioguanine and Tabloid).

Fludarabine (marketed as Fludara and 2-fluoro-ara-AMP).

Pyrimidine analogues:

Cytarabine (marketed as Ara-C and Cytosar-U). Also known as cytosine arabinoside, this drug has been used to treat Non-Hodgkin's Lymphoma.

Antifolates:

Methotrexate (marketed as Folex, Mexate, MTX, Methotrex—formerly Amethopterin). This drug has been used to treat Non-Hodgkin's Lymphoma. It is a folic acid analogue that indirectly inhibits DNA and RNA production by impairing the function of folic acid.

Note: The World Health Organization's Anatomical Therapeutic Chemical Classification System (ATC) classifies anti-metabolites as L01B.