methotrexate disodium: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
methotrexate disodium: clinical details
Prescribing considerations
- Initiation and supervision require clinicians experienced with methotrexate and its indication-specific risks.
- Confirm that the patient or caregiver can follow the prescription safely; document the named treatment day clearly for inflammatory indications.
- Review renal and hepatic function, infection risk, pulmonary history, alcohol use, interacting medicines and pregnancy potential before treatment.
- Assess dehydration, pleural effusion or ascites because these can increase exposure or delay elimination.
- Provide toxicity, sun-protection, safe-handling and overdose counselling.
Contraindications and cautions
- Hypersensitivity to methotrexate or formulation excipients
- Significant renal or hepatic impairment and alcoholism
- Pre-existing bone-marrow suppression or significant blood dyscrasia
- Severe active infection or immunodeficiency
- Stomatitis, oral ulceration or active gastrointestinal ulcer disease
- Pregnancy for non-oncological indications
- Breastfeeding
- Concurrent live vaccination
Monitoring
- Obtain baseline full blood count, liver tests, albumin and renal function; assess for lung disease and relevant chronic infections.
- Monitor full blood count, liver function and renal function regularly, with greater frequency after initiation, treatment changes or when toxicity risk is increased.
- Interpret trends as well as absolute values; declining blood counts, rising transaminases or deteriorating renal function may indicate toxicity.
- Promptly investigate mouth ulcers, infection, bruising, bleeding, respiratory symptoms, jaundice or reduced urine output.
Clinical pharmacology
Methotrexate is a folate antagonist transported into cells and retained through polyglutamation, producing prolonged intracellular antifolate effects. It is partly protein-bound and is eliminated mainly unchanged by glomerular filtration and active renal tubular secretion, making renal impairment and clearance interactions clinically important.
Formulation and product differences
- The oral solution must be measured with its supplied syringe, whose scale is in millilitres; it contains parabens, propylene glycol and sulphites and requires cytotoxic-handling precautions.
- The selected tablet contains lactose. Its score line is intended only to make swallowing easier and not to create equal portions.
- Oral bioavailability is variable; switching between oral and parenteral formulations requires specialist review.
methotrexate disodium preparations and strengths
Oral solution
Route: Oral
Strengths: 2 mg/mL
Tablet
Route: Oral
Strengths: 2.5 mg, 10 mg
methotrexate disodium interactions
Methotrexate has clinically important interactions, particularly with medicines that affect folate, blood-cell production, the liver or renal clearance. Check with a prescriber or pharmacist before starting prescribed, pharmacy or complementary products.
Trimethoprim or co-trimoxazole
The combination can cause severe bone-marrow suppression through additive antifolate effects and altered methotrexate handling; concurrent use should generally be avoided.
NSAIDs, including ibuprofen, naproxen and aspirin used for pain
These may reduce renal clearance and increase renal or methotrexate toxicity; over-the-counter use should be checked first.
Penicillin antibiotics, including amoxicillin
Reduced renal clearance may increase methotrexate toxicity, requiring clinical review and vigilance for mouth ulcers, sore throat, bruising or bleeding.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.