Methotrexate (MTX)

Discuss the use of methotrexate in IBD?

  • A Cochrane review showed that methotrexate (25 mg/week) injected intramuscularly for 16 weeks among patients with active treatment resistant Crohn’s disease may be an effective treatment.
  • Lower doses of methotrexate (12.5 to 15 mg/week) taken orally are not effective treatment for Crohn’s disease.
  • There is also evidence that methotrexate reduces the need for steroid treatment. This reduction in steroid use could reduce steroid induced side effects for people with chronic Crohn’s disease.
  • The mechanism by which it improves inflammatory bowel disease is not certain.
  • There is no evidence of it being effective in UC.

Discuss the side effects of methotrexate?

  • GI toxicity- nausea, vomiting, diarrhoea, and stomatitis. This may be limited by co-prescription of folic acid (1mg/day).
  • Hepatotoxicity- Withhold MTX if the aminotransferases doubles. Rechallenge may be attempted once LFTs normalise. Surveillance liver biopsy based upon the cumulative dose of MTX is not recommended. Use of MTX should be carefully considered in patients who are obese, diabetic and those who consume excess alcohol as the risk of hepatotoxicity may be increased.
  • Pneumonitis-This is rare.

Discuss the monitoring needed during methotrexate use?

Measurement of full blood count and liver function tests are advisable before and within 4 weeks of starting therapy, then monthly.

Discuss methotrexate in pregnancy?

Methotrexate is absolutely contraindicated as it is a potent abortifacient and is associated with congenital anomalies. Women and men taking methotrexate should stop this drug and use contraception for at least three months prior to conception.

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