6-mercaptopurine
methotrexate
azathioprine
cyclosporine

6-mercaptopurine => immuno suppressive drug (Purine!)
Methotrexate => I already know this as it's used for arthritis, also an inflammatory drug.

Note that purine is one of the 2 metabolites which are the building blocks of DNA/RNA. Anti-metabolites masquerade as a purine (azathioprine, mercaptopurine) or a pyrimidine, chemicals that become the building-blocks of DNA. They prevent these substances becoming incorporated in to DNA during the S phase (of the cell cycle), stopping normal development and division. (source: https://en.wikipedia.org/wiki/Antimetabolite) Thereby, they inhibit the overgrowth or overreactive inflammation process.

Mnemonics:
6 merry captain pure bred dogs go on the cyclo to met with each other at gaza.

Pure dogs = purine antimetabolites such as azathioprine, cyclosporine, 6-mercaptopurine & finally methotrexate.

6 merry captain pure bred dogs = 6-mercaptopurine
cyclo = cyclosporine
met = methotrexate
gaza = Azathioprine