Catagories of Chemotherapy Drugs:
In general, chemotherapy agents can be divided into three main
categories based on their mechanism of action.
Stop the synthesis of pre DNA molecule building blocks:
These agents work in a number of different ways. DNA building
blocks are folic acid, heterocyclic bases, and nucleotides, which
are made naturally within cells. All of these agents work to
block some step in the formation of nucleotides or deoxyribonucleotides
(necessary for making DNA). When these steps are blocked, the
nucleotides, which arethe building blocks of DNA and RNA, can
not be synthesized. Thus the cells can not replicate because
they can nnot make DNA without the nucleotides.
Examples of drugs in this class include 1) methotrexate (Abitrexate®),2)
fluorouracil (Adrucil®), 3) hydroxyurea (Hydrea®), and
4) mercaptopurine (Purinethol®).
Directly damage the DNA in the nucleus of the cell:
These agents chemically damage DNA and RNA. They disrupt replication
of the DNA and either totally halt replication or cause the manufacture
of nonsense DNA or RNA (i.e. the new DNA or RNA does not code
for anything useful).
Examples of drugs in this class include cisplatin (Platinol®)
and 7) antibiotics - daunorubicin (Cerubidine®), doxorubicin
(Adriamycin®), and etoposide (VePesid®).
Effect the synthesis or breakdown of the mitotic spindles:
Mitotic spindles serve as molecular railroads with "North
and South Poles" in the cell when a cell starts to divide
itself into two new cells. These spindles are very important
because they help to split the newly copied DNA such that a copy
goes to each of the two new cells during cell division. These
drugs disrupt the formation of these spindles and therefore interrupt
Examples of drugs in this class of 8) miotic disrupters include:
Vinblastine (Velban®), Vincristine (Oncovin®) and Pacitaxel