Methotrexate
- Oral / IVMethotrexateWeekly dosing
- Mechanism of Action
- Inflammatory diseases: inhibits interleukin-1 and interleukin 6 activity, and altering the numbers of different lymphocyte subsets.
- In cancer treatment: inhibits dihydrofolate reductase (DHFR), reducing synthesis of folate, which is involved in synthesis of the purine and pyramidine precursors required for DNA / RNA and cell proliferation.
- Pharmacology
- Serum half-life 8 hours
- Renal excretion - caution in combination with NSAIDs
Clinical Use
- Indications
- Inflammatory diseases - refractory inflammatory bowel disease, rheumatoid arthritis, psoriasis
- Chemotherapy - for certain cancers
- Adverse Effects
- Gastrointestinal - mouth ulcers, nausea / vomiting / abdominal pain
- Hepatotoxicity - elevated LFTs, cirrhosis
- Pulmonary - hypersensitivity pneumonitis
- Bone marrow suppression - leukopaenia / thrombocytopaenia / anaemia
Monitoring
- Monthly full blood count, renal function and LFTs.