Azathioprine

**Semantic type:** Nucleic Acid, Nucleoside, or Nucleotide|Pharmacologic Substance

**Definition:** A purine analogue with cytotoxic and immunosuppressive activity. Azathioprine is a prodrug that is converted by hepatic xanthine oxidase to its active metabolite 6-mercaptopurine (6-MP). 6-MP is further metabolized by hypoxanthine-guanine phosphoribosyltransferase (HGPRT) into 6-thioguanosine-5'-phosphate (6-thio-GMP) and 6-thioinosine monophosphate (6-thio-IMP), both inhibit nucleotide conversions and de novo purine synthesis. This leads to inhibition of DNA, RNA, and protein synthesis. As a result, cell proliferation may be inhibited, particularly in lymphocytes and leukocytes.

**Synonyms:** - 6-[(1-Methyl-4-nitro-1H-imidazol-5-yl)thio]-1H-purine - 6-[(1-Methyl-4-nitro-1H-imidazol-5-yl)thio]-1H-purine - AZA - AZATHIOPRINE - AZTP