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Methotrexate

The information on this page is specific to the rheumatology indications for methotrexate and how it is used by Dr Suppiah in the New Zealand context

What is methotrexate?

Methotrexate is in a class of medications called Disease Modifying Anti Rheumatic Drugs (DMARDs). This class of medication reduces joint damage and therefore protects from future disability.  It is the main medication used to treat rheumatoid arthritis.  If it is not enough on its own to control the disease, it forms the backbone to other treatments that are added.  It is also used in psoriatic arthritis, SLE, and peripheral joint problems in ankylosing spondylitis.  It can be used in certain forms of vasculitis.

It normally takes about 3 months to notice the benefit from methotrexate and up to 6 months for the peak effect.

Benefits of methotrexate

Methotrexate is one of the most effective treatments for rheumatoid arthritis.  It improves the symptoms and signs of inflammatory arthritis in over 60% of patients. It reduces joint damage and long-term disability.  In patients where there is insufficient benefit from methotrexate alone, combining it with other DMARDs or biological medications can improve the response. 

People often worry about the risks of methotrexate - but it actually prolongs life in patients with rheumatoid arthritis! 

How to take methotrexate

The typical dose is 2 x 10mg tablets (20mg) taken once per week - on the same day each week. It is best taken with dinner. Occasionally the dose is split over two consecutive days.

Alternatively, you may be prescribed an injection of methotrexate which is taken as a weekly injection under the skin.  The injection is slightly more effective and can have less stomach related side effects.  The dose range of the injection is up to 30mg/week.

A few days after the dose of methotrexate, a single 5mg dose of folic acid is taken to reduce side effects.

Side effects

Most patients get no side effects. If you do get side effects, they are usually mild but can include: mouth ulcers, nausea, vomiting, diarrhoea, headaches, fatigue and mental clouding.

More serious side effects are rare. You can get blood test abnormalities (and hence the need for regular blood tests), lung inflammation (<1%, and almost exclusively occurs in those that smoke). Hair thinning can occur but is reversible if the dose is reduced.

Methotrexate can sometimes make nodules worse in people who have nodules as part of their rheumatoid arthritis. 

Alcohol

Alcohol can increase the liver toxicity of methotrexate.

If you have no underlying liver problems, you can drink a maximum of 14 units of alcohol per week.  You should drink no more than 3 units in any one day (which is equivalent to about 2 small glasses of wine).  Ideally have 2-3 alcohol free days per week including the day methotrexate is taken.


Monitoring

Blood tests to check kidney function, liver function and full blood count are needed every month for the first few months.  If stable the frequency of testing can be extended to every 2-3 months.

Response to treatment is usually assessed every 2-3 months.  If there is inadequate benefit then other medications may be added to methotrexate.

Pregnancy

Methotrexate is teratogenic, which means that if a woman gets pregnant when taking this medication there is a risk that the foetus will have a malformation or the pregnancy will miscarry. Women of child bearing age should have appropriate contraception in place prior to starting methotrexate.

If women on methotrexate want to become pregnant, they will need to stop methotrexate for 6 months prior to trying to concieve.  You should not breast feed whilst taking methotrexate.

It is unclear whether it is safe for males to father children whilst on methotrexate.  Some small studies suggest it may be safe, but is generally recommended that males come off the medication for at least 4 months prior to fathering children.

Vaccination

The local recommendations for vaccines if you are on methotrexate are:

1. Influenza vaccine (yearly)
2. Vaccination against pneumococcal disease (Prevenar 13 and Pneumovax 23 - every 5 years)
3. Vaccination against haemophilus influenza b (Hiberix)
4. Vaccination against meningococcal disease (Menectra)

In general, you should not have live vaccines (e.g. MMR, yellow fever, typhoid).  The only exception is the Shingles vaccine which is thought to be okay as long as methotrexate is not being used in combination with other DMARDs or biologic medications.


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