Gastroenterology - Azathioprine in Auto Immune Hepatitis (AIH)

Your doctor is planning to start you on Azathioprine. This information leaflet is designed to answer some questions that you may have.

Why do I need Azathioprine?

Azathioprine is an effective drug used in the treatment of AIH. Mercaptopurine is a metabolite of Azathioprine that can be used in some circumstances.

Azathioprine is often used in patients whose AIH rapidly deteriorates when steroids are stopped or reduced, and in patients with significant liver inflammation due to AIH.

It acts by suppressing the body’s immune system, in order to reduce the inflammatory process in the body. Hence, it is always used with caution.

Azathioprine has been shown to be effective in maintaining remission (controlling disease activity) in AIH and is therefore used to control the disease.

You will have the opportunity to discuss your treatment with your consultant when a decision is made that this medication may benefit you.

You will also have the opportunity to discuss the details of this medication with the Gastroenterology Nurse Specialist (GNS) during which you will be given an information leaflet to take away with you for future reference.

What happens before I start my treatment?

You will need to have a blood test before you start azathioprine to check your blood cells and your liver function.

An enzyme test (TPMT test) will be performed to decide the dose that is safe for you to take. This enzyme removes azathioprine from the body. Low levels of TPMT could mean that you are at an increased risk of side effects.

What dose do I need to take?

Azathioprine is taken as a tablet once or twice a day, swallowed whole, after food. The dose is weight based, and the usual dose is between 1.5 - 2.5mg per kilogram body weight.

You will usually commence at 50 mg, but this may be eventually adjusted as necessary. If you miss a dose, take it as soon as you remember. If it is less than 12 hours before your next dose, do not take the missed dose, but take your next dose at your normal time.

How long does it take to work?

Azathioprine or Mercaptopurine usually takes between 6 weeks and 3 months to become fully effective. During that time, you may need to take corticosteroids to maintain control of your disease.

Possible side effects

Azathioprine has been used for many years to treat AIH, but like all medicines, it can have side effects. Some side effects last only for a short period while the body gets used to azathioprine or mercaptopurine.

Common side effects:

• Nausea
• Mild aches and pains
• Increased risk of minor infections
• Rashes
• Fever
• Joint pains

Other side effects may include:

• Low white cell count
• Raised liver function
• Pancreatitis

These side effects are rare and are often reversible on stopping or reducing the dose.

While on treatment, there is a risk of certain cancers particularly lymphoma and non-melanoma skin cancer. The incidence remains low, and it is regarded that the benefit of treatment outweighs the small risk involved.

You can minimise the risk of skin cancer by ensuring that you have adequate skin protection when out in the sun by using a high SPF sunscreen. You should inform the GNS if you are notice any changes to your skin.

How long will I need to take Azathioprine?

If well tolerated, Azathioprine is given as a long term medication. Your consultant will discuss with you the duration of treatment as this varies between individuals. You should not stop taking Azathioprine without consulting with the consultant or GNS.

What tests will I need to have while on Azathioprine?

You will need weekly blood tests x 6 weeks; monthly blood tests for 3 months and then 3 monthly bloods while you are taking the medication.

Can I get a repeat prescription from my GP?

Many GPs will decline to do this so please contact the GNS or your consultant’s secretary for a prescription to be issued. You should request your prescription when you have approximately 2 weeks supply left.

Should I receive vaccinations?

We would recommend that you have influenza, pneumonia and Covid vaccinations.

Azathioprine - pregnancy and breast feeding

Azathioprine appears to be safe in pregnancy. Discontinuing the medication is associated with high relapse rates of AIH.

Azathioprine and mercaptopurine are detectable in breast milk but levels are low. Breast feeding is considered safe.

Will it interfere with my other medications?

Certain medications can interfere with Azathioprine. Please inform your health care professionals that you are taking Azathioprine.

Talk to the pharmacist when buying over the counter medications to ensure that there are no interactions with azathioprine.

Can I drink alcohol?

You should only drink alcohol in small amounts because azathioprine and alcohol can interact and damage your liver. Discuss this with your doctor.