PEBC: What You Need to Know: Methotrexate

Indications: Rheumatoid arthritis, psoriasis, certain cancers

Dose: most of the time weekly or cyclical basis

-tablets: with food to reduce nausea

-may be given subcutaneously, intramuscularly and intravenously depending on indication

-large doses require adequate hydration (for kidney protection)

Contraindications:

-pregnancy (off-label it is used to induce abortion)

Adverse Effects:

-mouth ulcers, gastric ulcers and nausea - due to folate depletion - supplement with folic acid at least 24 hours after methotrexate dose

-fatigue

-alopecia

-renal failure: adequate hydration is key

-pneumonitis

-increased liver function tests

Interactions:

-NSAIDs may increase the risk of kidney failure (more likely with high dose methotrexate)

-careful with live vaccines due to immunosuppression by methotrexate

-proton pump inhibitors decrease methotrexate renal clearance (usually for high dose methotrexate)

-trimethoprim - duplication with methotrexate and can lead to increased myelosuppression