Bright Sight

Oliver Backhouse, Consultant Eye Surgeon www.cataract.org.uk

Treatment with Methotrexate

METHOTREXATE is a drug used to suppress the immune system. The immune system is responsible for fighting infections, but there may be circumstances where it is necessary to suppress its action. Methotrexate is also used to treat auto-immune conditions. These conditions can result, for a variety of reasons, because the body’s immune system fails to recognise a part of itself, and reacts against it. This causes inflammation and scarring of the part affected. Some inflammations inside the eye (uveitis) are auto-immune diseases.

Methotrexate is taken by mouth in the form of tablets. The dose is around 12.5 – 25mg once a week. Folic acid is taken on all the other days of the week. Do make sure your dose is correct as tablets can look similar. Methotrexate works by preventing some cells from dividing and reproducing so quickly and therefore reduces the ability of these cells to cause inflammation. If you miss your dose then you can take it over the next 2 days but if it is longer than this then just wait for your next regular dose on the specified day you usually take your Methotrexate. It can also be given by weekly injection is sickness is a problem.

Most patients who use Methotrexate to treat uveitis are already using steroids (prednisolone). Information on this drug is also available. Methotrexate is usually given to reduce the dose of prednisolone in order to reduce side-effects. If Methotrexate is to be prescribed for your eye inflammation, you will need to know about potential side-effects of the drug, and the regular tests that will be performed in order to minimise problems.

1. The bone marrow and blood cells.

Methotrexate acts by preventing some white blood cells from causing inflammation. In a few patients there is a more generalised reduction in the number of white blood cells, which is undesirable. Rarely the red blood and clotting cells are also affected and this is also undesirable. There will be blood tests every few weeks and then every 3 months when stable.

Severe problems are rare and most patients have no problems with their bone marrow and blood counts. Bruising of the skin, bleeding from the gums, severe sore throat or infection should be reported to your doctor for an immediate examination and blood test.

2. Stomach irritation.

A few patients feel slightly sick when starting to take Methotrexate. Taking the table one hour after food in the evening may prevent them causing sickness. Rarely more severe irritation occurs. If this does occur it should be reported to your doctor immediately.

3. Infection.

Methotrexate alone, taken in small to moderate doses (as for the treatment of uveitis) is unlikely to lead to an increased infection risk. However it is usually used with prednisolone initially. When these 2 drugs are used together there is a greater infection risk than either drug used alone. Information on this topic is covered in the Prednisolone information leaflet.

4. Others.

If you are a woman, it is important you do not become pregnant when using Methotrexate as there is a small risk of damage to a baby. If necessary you should take contraceptive precaution. Whether male or female, a period of 6 months is advised to wait having stopped Methotrexate before trying for a baby. In a few people, hair loss can occur but is not common and unlikely to be severe. Occasionally the kidneys or liver are also affected and so regular bloods tests will be needed to make sure this is not happening. There is a theoretical risk of increased malignancy but his is extremely unlikely at the low doses used in uveitis.

Other side-effects that can affect the Lungs are rare as are skin rashes, ulcers and diarrhoea.

Used properly and with safety monitoring with blood tests, problems rarely arise. However, Methotrexate is a powerful drug. There is no drug useful for the treatment of uveitis that is entirely free of potential or actual side-effects.

You should notify your doctor if any of the following occur:

  • Infections including fever, chills or sore throat.
  • Unexplained new skin rash, ulcerations or soreness of skin
  • Yellowing of the skin or generalized itching
  • Bleeding gums, black tarry stools or unexpected bleeding or bruising
  • Chest pain, difficulty breathing or a dry, persistent cough
  • Sore mouth or mouth ulcers
  • Severe and continuing diarrhoea, vomiting or stomach pains

See your doctor if you develop any new symptoms after starting Methotrexate. Always let your doctor know you are taking Methotrexate if other medication is to be given as well incase there is interaction. The use of ‘Live’ vaccines should be avoided. Alcohol should be in moderation.