Methotrexate

Cytostatic · Folic acid antagonist

Indications

See under dosage.

Dosage

Adults: Antineoplastic: Burkitt's Lymphoma: Stages I-II: Orally: 10-25 mg/day for 4-8 day for several courses; separate by 7-10 day rest period. Lymphosarcomas: Stage III: Orally: 0.625-2.5 mg/kg/day. Leukaemia: Induction: 3.3 mg/m² with prednisone every day. Remission Maintenance: 15 mg/m² Orally/IM twice wkly or 2.5 mg/kg IV every 14 day. Mycosis fungoides: 5-50 mg every wk. If poor response, give 15-37.5 mg twice wkly. Osteosarcoma: Initial: 12 gm/m² IV, increase to 15 gm/m² if peak levels of 1000 micro-molar not reached at end of infusion. Choriocarcinoma/trophoblastic diseases: Orally/IM: 15-30 mg every day x 5 day, rest >1 wk & repeat 3-5 times. Rheumatoid arthritis: Initial: 7.5 mg once wkly or 2.5 mg every 12 hr x 3 doses once wkly. Max: 20 mg/wk. Reduce to lowest effective dose. Psoriasis: Usual: 10-25 mg/wk Orally/IV/IM until adequate response achieved or use 2.5 mg every 12…

Administration

It may be administered IM, IV or IT. IV administration may be slow push, short bolus inf or 24-42 hour continuous inf. Dilute powder with D5W or NS to a conc. of = 25 mg/mL (20 mg and 50 mg vials)and 50 mg/mL (1 gm vial). Intrathecal solutions may be reconstituted to 2.5 to 5 mg/mL with NS, D5W, LR or Elliott's B solution. Use preservative free preparations for IT or high dose administration. Stability: Store at 20°C-25°C (68°F-77°F); excursions are permitted to 15°C -30°C (59°F-86°F). Protect from light.

Adverse Effects

Bone marrow depression, GI upset, hepatotoxicity, skin reactions, opportunistic infections, urino-genital disorders, decreased fertility and pulmonary disease and CNS disturbances, myelosuppression, headache, dizziness, drowsiness, fatigue, stomatitis, anorexia, hepatotoxicity, skin reactions, infections. Reports of malignant lymphoma, haematemesis (discontinue), radiation recall, encephalopathy.

Risk Factor (Pregnancy/Lactation)

Pregnancy: Contraindicated in pregnancy. Lactation: Contraindicated or not recommended. Contraindications: Severe renal or hepatic impairment, active infectious disease, immune deficiency syndrome, serious anaemia, leukopenia, thrombocytopenia, AIDS, pre-existing blood dyscrasias, alcoholism, GI ulceration, stomatitis. Precautions: Hematological depression, chronic hepatic disease, psychiatric disorder, ascites, elderly, Perform blood, urine, hepatic and renal test. Pulmonary or mild to moderate renal impairment, inactive chronic infections, ascites, pleural effusion, diabetes. Long-term therapy. Elderly. Monitor oromucosal changes before, during and after therapy. Perform chest X-ray before therapy. Risk of pneumonitis and Pneumocystis jirovecii pneumonia, monitor patients and advise them to report symptoms of dyspnoea, cough or fever. Risk of diarrhoea, vomiting, ulcerative…

Interactions

Protein bound drugs, alcohol, live vaccine, folic acid, folate antagonist, anticonvulsants, NSAIDs, cyclosporin, mercaptopurine, proton pump inhibitors, theophylline, other myelotoxic, nephrotoxic or hepatotoxic agents (e.g., leflunomide, procarbazine, 5-FU), live vaccines, folic or folinic acid, folate antagonists, cytostatic agents, immunomodulators, NSAIDs, retinoids, antibiotics, sulfasalazine, azathioprine, mercaptopurine, caffeine, nitrous oxide, colestyramine.

Advice to Patient

Report immediately if there is redness/swelling/burning/pain at infusion or injection site or of you experience increased fatigue, rash, difficulty in breathing. Contact prescriber if there is fever, chills, unusual bleeding or bruising, chest pain, palpitations, fast heartbeat, black or dark coloured stool, dark coloured urine, blood in stool, difficulty in breathing, constant GI disturbances, diarrhoea, constipation, pain on urination, change in urinary pattern, sore throat, yellowing of skin or eyes. Take sufficient amount of fluids (2-3 litres per day) to maintain hydration, unless restricted by the prescriber. Avoid alcohol during therapy. Take small, frequent meals to maintain good nutritional status. Avoid highly crowded places to prevent infection. Do not get vaccinated without consulting prescriber. Using soft toothbrush, cotton swabs, regular mouth care, frequent rinses may…

Pharmacokinetics

Onset of action: Antirheumatic: 3 to 6 weeks; additional improvement may continue longer than 12 weeks. Absorption: Oral: Highly variable; dose dependent; decreased absorption at higher doses (pediatric patients: >40 mg/m²; adult patients: >80 mg/m²); possibly due to saturation effect. IM injection: Complete. Metabolism: Partially metabolized by intestinal flora (after oral administration). Bioavailability: Oral: Children: Highly variable: 23% to 95%. Adults: Low doses (=30 mg/m²): Approx. 60%. Half-life elimination: Children: ALL: 0.7 to 5.8 hours (dose range: 6.3 to 30 mg/m²); pJIA: 0.9 to 2.3 hours (dose range: 3.75 to 26.2 mg/m²). Adults: Low dose: 3 to 10 hours; High dose: 8 to 15 hours. Time to peak, serum: Oral: Children: 0.7 to 4 hours (reported for a 15 mg/m² dose). Adults: 1 to 2 hours. IM: Children and Adults: 30 to 60 minutes. Excretion: Dose and route dependent: IV: Urine…

Brands with this active ingredient

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