methotrexate: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
methotrexate: clinical details
Prescribing considerations
- Initiate and supervise through clinicians experienced with methotrexate; ensure the patient or carer understands the labelled schedule and overdose risk.
- Review renal and hepatic function, blood counts, infection risk, pulmonary history, pregnancy potential, vaccination status and interacting medicines before treatment.
- Consider formulation suitability, dexterity, swallowing ability, adherence risk and potentially greater bioavailability after switching from oral to parenteral treatment.
- Assess pleural effusion or ascites because pathological fluid collections can prolong elimination and increase toxicity.
Contraindications and cautions
- Product-specific contraindications commonly include hypersensitivity, severe hepatic or renal impairment, clinically important blood dyscrasias, serious infection or immunodeficiency, active oral or gastrointestinal ulceration, pregnancy for non-oncology use and concurrent live vaccination.
- Breastfeeding is contraindicated in the selected SmPCs.
- The concentrated hospital injection is hypertonic and must not be administered intrathecally.
Monitoring
- Establish baseline full blood count, renal and liver function; assess for lung disease and screen for relevant chronic infections according to indication and risk.
- Repeat blood count, liver and renal tests closely after initiation or treatment changes and regularly once stable; increase frequency for toxicity risks or interacting medicines.
- Act on adverse trends as well as absolute results. New mouth ulcers, infection, bruising, respiratory symptoms or reduced renal function warrant prompt review.
Clinical pharmacology
Methotrexate competitively inhibits dihydrofolate reductase, disrupting reduced-folate pathways and DNA synthesis. Renal elimination is clinically important; impaired kidney function or medicines that reduce clearance can rapidly increase exposure.
Formulation and product differences
- Tablets are oral and the score line on the selected product is for easier swallowing, not equal division.
- Jylamvo is a ready-to-use oral solution measured in millilitres with its supplied syringe; it should be shaken and followed with water.
- Metoject PEN is a fixed-content, single-use subcutaneous device requiring patient or carer training.
- The concentrated hospital injection can be administered intravenously, intramuscularly or intra-arterially but is not suitable for intrathecal use.
- Oral and injectable formulations are not directly interchangeable because oral bioavailability is variable.
methotrexate preparations and strengths
Oral solution
Route: Oral
Strengths: 2 mg/mL
Tablet
Route: Oral
Strengths: 2.5 mg, 10 mg
Injection
Route: Parenteral
Strengths: 2.5 mg/mL, 25 mg/mL, 100 mg/mL
methotrexate interactions
Check all prescribed, pharmacy and complementary products with a clinician or pharmacist. Important examples include:
Trimethoprim or co-trimoxazole
Avoid where possible because additive antifolate effects can cause severe, sometimes delayed bone-marrow suppression.
NSAIDs, including ibuprofen and high-dose aspirin
They may reduce renal clearance and increase toxicity, particularly with kidney impairment or intensive cancer treatment; do not self-treat without checking.
Penicillin antibiotics
They may reduce methotrexate clearance, so toxicity symptoms and monitoring requirements should be reviewed.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.