Methotrexate

Nursing pharmacology study reference (NCLEX-style monograph). Numeric values are standard teaching ranges for study and must be verified against current manufacturer labeling before clinical use. This is educational content, not prescribing guidance.

Methotrexate (brand names Trexall, Otrexup) — Disease-modifying antirheumatic drug, antineoplastic, immunosuppressant; Antimetabolite (folate antagonist).

Identification

• Therapeutic class: Disease-modifying antirheumatic drug, antineoplastic, immunosuppressant.
• Pharmacologic class: Antimetabolite (folate antagonist).

Pharmacology

• Mechanism of action: Inhibits dihydrofolate reductase to reduce cell proliferation and inflammation.
• Onset / peak / duration: Antirheumatic effect over weeks; cancer dosing is higher.
• Half-life / therapeutic level: Variable; high-dose oncology use monitors levels.

Clinical use

• Indications: Rheumatoid arthritis, psoriasis, certain cancers, ectopic pregnancy, severe Crohn disease.
• Usual dose, route, frequency: Rheumatoid arthritis: once weekly PO or SubQ (never daily); cancer dosing differs.
• Maximum dose / adjustments: Reduce in renal impairment; add folic acid for rheumatic use; leucovorin rescue for high-dose oncology.

Safety

• Contraindications: Pregnancy and breastfeeding, significant hepatic or renal disease, alcohol use disorder, blood dyscrasias, active infection.
• Black box warning: Multiple: hepatotoxicity, myelosuppression, serious and potentially fatal infections, pulmonary toxicity, severe skin reactions, GI toxicity, renal damage at high doses, secondary malignancy, and embryo-fetal toxicity (contraindicated in pregnancy); should be prescribed by clinicians experienced with its use.
• Interactions: NSAIDs and salicylates and probenecid (raise methotrexate toxicity), trimethoprim/sulfamethoxazole (marrow suppression), proton pump inhibitors, hepatotoxic drugs and alcohol.
• Pregnancy / lactation: Contraindicated; effective contraception required.
• High-alert: No.

Adverse effects

• Common side effects: Nausea, mouth sores, fatigue, hair thinning.
• Serious effects to report: Bone marrow suppression (infection, bruising), hepatotoxicity, pulmonary toxicity (cough, dyspnea), severe mucositis.
• Antidote / reversal: Leucovorin (folinic acid) rescue; glucarpidase for severe high-dose toxicity.

Nursing process

• Assessment before administration: CBC, LFTs, renal function, pregnancy status, infection, confirm weekly schedule for rheumatic use.
• Interventions during therapy: Confirm once-weekly dosing for rheumatic disease (daily dosing has caused fatal errors); give folic acid; monitor labs.
• Monitor: CBC, LFTs, renal function, respiratory status.
• Evaluation / expected outcome: Reduced joint inflammation or disease control.

Patient teaching

• Patient teaching: Take exactly once a week (mark the calendar); take folic acid as prescribed; avoid alcohol; use reliable contraception; report mouth sores, fever, or cough.
• Notify provider if: Fever or infection, mouth sores, cough or breathlessness, easy bruising, yellowing of skin.
• Administration tips: Once weekly for rheumatic disease; never daily; folic acid supplementation.