Azathioprine – a tablet used for suppressing immune system

Azathioprine – a tablet used for suppressing immune system

Azathioprine is a medicine used for organ transplants and many autoimmune conditions

Generic name: Azathioprine [ ay-za-THYE-oh-preen ]
Brand names: Azasan, Imuran
Uses: Prevent transplant organ rejection and a variety of autoimmune conditions
Tablet form: 50 mg; 75 mg; 100 mg
Drug class: Purine anatagonist

What is azathioprine?

• Azathioprine is an immunosuppressant medication.
• It belongs to a class of drugs called purine antagonist, which work by interfering with the DNA production of certain cells in the immune system.

Uses

Azathioprine is used to treat people with:

• Organ transplants (to prevent the body from rejecting a new kidney, heart, lung or liver)
• Rheumatoid arthritis (usually when other treatments haven’t worked)
• Inflammatory Bowel Disease (IBD), such as Crohn’s disease (CD) or ulcerative colitis (UC)
• Systemic Lupus Erythematosus (SLE)
• Autoimmune hepatitis

Dosage

• Taken once or twice daily, usually with or after food to reduce stomach upset.
• The dose is highly individualised, calculated based on your body weight.
  • After a kidney transplant, the maintenance dose is 1–2.5 mg/kg daily.
• It is a slow-acting medicine; it can take weeks or even months to feel the full benefit.

Side-effects

Common side-effects

• Nausea and vomiting (especially when starting treatment)
• Loss of appetite
• Increased sensitivity to sunlight (increased risk of skin cancer)
• Increased risk of minor infections (like colds or flu)

Less common (and more serious) side-effects

• Bone marrow suppression: A significant drop in white blood cells, red blood cells, or platelets (leading to easy bruising or bleeding).
• Liver problems: Jaundice (yellowing of the skin or eyes) or dark urine.
• Pancreatitis: Severe abdominal pain.
• Severe infections: Due to a weakened immune system.
• Allergic reactions: Such as a sudden rash or fever.

Note: If you develop a fever, unexplained bruising, or a sore throat, contact your doctor immediately.

How it works

• It works by reducing the activity of the body’s immune system.
• It does this by blocking the production of T and B lymphocytes (white blood cells) – by disrupting their DNA/RNA synthesis. Its exact mechanism is not entirely understood.
• By limiting the production of lymphocytes, it helps prevent the body from attacking its own healthy tissues (what happens in autoimmune disease) or rejecting a transplanted organ.
• It is a prodrug for 6-mercaptopurine (6-MP).

Monitoring

Because azathioprine affects the blood and liver, regular monitoring is essential:

• Frequent blood tests: Initially every week or two, then moving to every few months once stable. These check your Full Blood Count (FBC) and Liver Function Tests (LFTs).
• TPMT test: Most patients have a blood test before starting to check for an enzyme called TPMT. If this enzyme level is low, you are at a much higher risk of side effects.
• Skin checks: Regular monitoring for new moles or skin changes due to increased photosensitivity.