azathioprine + cyclophosphamide

Azathioprine + cyclophosphamide is a combination of two immunosuppressive small molecule drugs, each with distinct but complementary mechanisms of action. Azathioprine is a prodrug that converts to 6-mercaptopurine in the body and inhibits purine synthesis, thereby suppressing DNA and RNA synthesis in rapidly dividing cells such as lymphocytes. Cyclophosphamide is an alkylating agent that crosslinks DNA strands, leading to cell death, particularly affecting proliferating immune cells. This combination has been explored for use in severe autoimmune diseases (such as lupus and vasculitis) and organ transplantation settings where potent immunosuppression is required[3][5][8]. Both agents are associated with significant risks including bone marrow suppression, increased infection risk, hepatotoxicity (azathioprine), hemorrhagic cystitis (cyclophosphamide), and potential carcinogenicity[4][7]. The combination may be considered when monotherapy or other regimens are insufficient; however, it carries an increased risk of toxicity and requires close monitoring[6].