Methotrexate

Methotrexate is an immunosuppressant, and also slows epidermal cell proliferation. It is used as oral therapy for severe unresponsive psoriasis. Methotrexate is potentially toxic, and the prescriber needs to be familiar with the appropriate precautions. Although methotrexate can be prescribed in primary care for severe psoriasis, therapy should be initiated by, or prescribed in conjunction with, a dermatologist.

Note: Methotrexate therapy for severe psoriasis should be initiated by, or prescribed in conjunction with, a dermatologist.

Before starting methotrexate therapy, prescribers should:

  • exclude pregnancy
  • screen for pre-existing conditions and infections
  • check vaccination status
  • perform a medication review and check drug interaction information—methotrexate has clinically significant interactions with many other drugs, which can reduce its efficacy or increase its toxicity
  • discuss with the patient the harms and benefits of taking the drug
  • inform the patient that the drug is taken weekly, not daily.
Note: Ensure the patient understands that methotrexate is taken weekly, not daily.

Methotrexate is teratogenic—it is contraindicated in females during pregnancy, and in both males and females in the 6 months before conception. Counsel both male and female patients on the serious risk to the fetus if conceived during or within 6 months of methotrexate therapy1. If either partner is receiving methotrexate therapy, pregnancy should be avoided and reliable effective contraception should be used during this period. For more details, refer to the product information.

Note: Methotrexate is teratogenic—it is contraindicated in females during pregnancy, and in both males and females in the 6 months before conception.

Folic acid is taken during methotrexate therapy to minimise adverse effects. For severe psoriasis, specialists may recommend:

methotrexate 5 to 10 mg orally, once a week, on the same day each week. Increase dose slowly as required to a maximum of 20 mg once a week (average maintenance dose is 10 to 20 mg once a week). Monitor full blood count, kidney function and liver biochemistry regularly2 methotrexate methotrexate methotrexate

PLUS

folic acid 5 to 10 mg orally, per week (preferably not on the same day the methotrexate is taken). folic acid folic acid folic acid

Lower doses of methotrexate are prescribed for patients who are elderly or have impaired kidney function, because adverse effects are more common in these patients.

Psoriasis is a chronic condition that usually requires long-term treatment. The duration of methotrexate therapy should be limited because toxicity is cumulative. When the skin is clear, the dose should be gradually reduced over a few months. The patient may achieve remission, which can last for months or years; however, if the condition flares when the dose is reduced, the patient may require long-term treatment, in consultation with a dermatologist.

1 Although it is recommended that both male and female patients avoid methotrexate use within 6 months of conception, the optimal time interval between cessation of treatment (of either partner) and pregnancy has not been clearly established.Return
2 Monitoring frequency of methotrexate is determined by the specialist (eg at baseline and every 2 to 4 weeks for the first 3 months, then every 3 months). More frequent monitoring is usually required at the start of treatment, during dose titration or change of route of administration, or as clinically indicated. For more information on monitoring, refer to the product information.Return