Azathioprine

Key points

• Azathioprine: metabolised to 6-mercaptopurine → purine synthesis inhibitor → immunosuppression.
• Side effects: myelosuppression (dose-related), deranged LFTs, pancreatitis, hypersensitivity reactions.
• TPMT (thiopurine methyltransferase) deficiency → severe myelosuppression; check TPMT before starting.
• Interaction: allopurinol inhibits xanthine oxidase → dangerously ↑ azathioprine levels (reduce dose).
• Monitor FBC and LFTs regularly.

Decision points in this pathway

• Patient needs allopurinol?

The full step-by-step algorithm, including what to do at each branch, opens in the app for approved members.