Main categories of these drugs include: *base analogues (altered nucleobases) – structures that can substitute for a normal nucleobases in nucleic acids. This means that these molecules are structurally similar enough to the basic components of DNA that they can be substituted in. However, since they are slightly different from the normal bases after they are incorporated into the DNA, the DNA production is halted and the cell dies. *purine analogues – mimic the structure of metabolic purines, the larger bases incorporated into DNA as adenosine and guanosine. *Examples: Azathioprine, Thiopurines, and Fludarabine *pyrimidine analogues – mimic the structure of metabolic pyrimidines, the smaller bases incorporated into DNA as cytosine and thymine. *Examples: 5-Fluorouracil, Gemcitabine, and Cytarabine *nucleoside analogues – nucleoside alternatives that consist of a nucleic acid analogue and a sugar. This means these are the same bases as above, but with an added sugar group. For the nucleoside analogues either the base or the sugar component can be altered. They are similar enough to the molecules used to build cellular DNA that they are incorporated by the cell into its DNA, but different enough that after being added the cell's DNA they stop cell growth. *nucleotide analogues – nucleotides alternatives that consist of a nucleic acid, a sugar, and 1–3 phosphates. This means these molecules look exactly like the pieces used to build DNA in a cell and can be incorporated into a growing cell's DNA. However, because they are analogues and therefore slightly different than regular nucleotides, causing the cell’s growth to be halted and the cell to die. *antifolates – chemicals that block the actions of folic acid (vitamin B9) which is needed to build DNA and allow cells to grow. Nucleobases, nucleotides, and nucleosides
Antimetabolite
Toxicophore
Topoisomerase inhibitor
Immunoconjugate
Monoclonal antibody
Antioxidant
Antiparasitic
Antiviral drug