Methotrexate for Psoriasis

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What is Methotrexate?

Methotrexate  was discovered to be effective in clearing psoriasis in the 1950s and was eventually approved for this use by the FDA in the 1970s. It belongs to the group of drugs known as Immunosuppressants .

How does it work?

In psoriasis, methotrexate works by preventing the excessive division and multiplication of skin cells that causes the skin scaling and raised plaques in this condition. It is used when the condition is severe and unresponsive to conventional treatments.

In low doses methotrexate can also affect the division of normal, healthy cells, and it has the potential to produce serious side effects. For this reason, treatment with methotrexate is usually only initiated by hospital specialists, and regular blood tests are needed to monitor for potential side effects.

Who can get it?

Methotrexate is for use in adults with severe psoriasis. Methotrexate is often prescribed for severe plaque psoriasis, erythrodermic psoriasis and acute pustular psoriasis. In addition, the drug can be used to treat psoriatic arthritis, a psoriasis-related condition similar to rheumatoid arthritis. Methotrexate can be highly effective in reducing the painful symptoms of psoriatic arthritis.

How is it used?

Maxtrex
For the treatment of severe psoriasis take 10 - 25 mg orally, once a week. Dosage should be adjusted according to the patient's response and the haematological toxicity. The prescriber may specify the day of intake on the prescription.

Methotrexate oral solution
The usual dose is 10mg – 25mg (5ml – 12.5ml) taken once weekly. The planned weekly dose can be administered as three divided doses over 24 hours. As necessary, the total weekly dose can be increased up to 25mg. Thereafter the dose should be reduced to the lowest effective dose according to therapeutic response which is most cases is achieved within 4 to 8 weeks.

Metoject
Take 7.5mg by subcutaneous injection once weekly increasing gradually depending on individual tolerance and disease activity. Maximum weekly dose 25mg.  After desired response reduce gradually to lowest effect dose.

Ziatal
7.5 mg by subcutaneous or intramuscular injection once a week increasing gradually according to response with a maximum weekly dose of 25mg.  After desired response reduce gradually to lowest effect dose.

What are the side effects?

Taking methotrexate can cause the following potential side effects:

  • Nausea*
  • Tiredness
  • Difficulty sleeping
  • Light-headedness
  • Mouth ulcers**
  • Vomiting
  • Headache
  • Easy bruising and bleeding
  • Fever
  • Diarrhoea with blood in the stool
  • Chills

*Sometimes nausea can be helped by drinking milk or eating before taking the medication. Severe nausea may mean the dose is too high. Studies have shown that taking folic acid in doses of 1 to 5 milligrams (mg) a day can reduce nausea and other side effects associated with methotrexate. However, some studies have shown that folic acid may reduce methotrexate's effectiveness. Folic acid should not be taken on the same days that methotrexate is used. Check with your doctor.

**If sores appear in the mouth, the dose may be too high.

These side effects are generally manageable with careful monitoring and patient education.

How do I get methotrexate?

Methotrexate is available by prescription

Further guidance

National Institute for Health and Care Excellence (NICE) guidance
Scottish Medicine Consortium guidance
All Wales Medicines Strategy Group
For Northern Ireland, the Department of Health, Social Services and Public Safety (DHSSPS) provide reviews and advice

Methotrexate is known commercially as Maxtrex which is marketed in the UK by Pfizer Ltd, Methotrexate oral solution which is marketed in the UK by Rosemont Pharmaceuticals Limited, Metoject which is marketed in the UK by Medac and Ziatal which is marketed in the UK by Nordic.