Methotrexate

Dosage Forms

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Tablet

2.5 mg

Injection

50 mg/ml

Uses

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Severe rheumatoid arthritis (unresponsive to first line treatment)
Severe, unresponsive psoriasis
Acute lymphoblastic leukaemia
Non-Hodgkin’s lymphoma
Soft-tissue and osteogenic sarcomas
Solid tumours (breast, lung, head and neck, bladder, cervical, ovarian, testicular carcinoma)

Dose and Duration

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Rheumatoid arthritis

Adult: 7.5 mg orally once a week

Severe psoriasis

Adult: 10−25 mg orally once a week. Adjust dose according to patient’s response and haematotoxicity

Cancers

Adult: Initially, give test dose of 5−10 mg IV to detect adverse events. Then, doses not exceeding 30 mg/m² on not more than 5 consecutive days. A rest period of 2 weeks is recommended between treatments, in order to allow bone marrow to return to normal

Leukaemia in children (maintenance dose)

Child: 15 mg/m² once weekly orally

Contraindications

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Severe renal impairment
Severe hepatic impairment
Presence of pleural effusion or ascites
Hypersensitivity to methotrexate

Side Effects

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Skin reactions
Myelosuppression
Anorexia, abdominal discomfort, dyspepsia
Mucositis (gingivitis, pharyngitis, enteritis)
Gastrointestinal bleeding
Hepatic toxicity
Renal failure
Reduced fertility (reversible on stopping treatment)
Menstrual disturbances
Pulmonary toxicity
Headache, drowsiness, blurred vision
Stevens-Johnson syndrome

Interactions

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Nitric oxide: (increased methotrexate antifolate effect)
Cotrimoxazole: (increased haematological toxicity)
Pyrimethamine: (increased antifolate effect)
Clozapine: (increased risk of agranulocytosis)
Cisplatin: (increased pulmonary toxicity)
Leflunomide: (risk of toxicity)
Acitretin: (increased risk of hepatotoxicity)
Live vaccines: (risk of developing disease)
NSAIDS, probenecid, penicillins, ciprofloxacin, chloramphenicol, tetracyclines, thiazide diuretics: (increased risk of methotrexate toxicity)

Patient Instructions

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Use adequate contraception during treatment and for 3 months after therapy
Seek medical attention if you develop cough, fever or difficult breathing

Pregnancy

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Do not use

Breast-feeding

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Discontinue breastfeeding

⚠️ Caution

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Monitor full blood count before and during treatment
Folinic acid given after methotrexate administration prevents methotrexate-induced mucositis/myelosuppression
Reduce dose in elderly patients
Adjust dose based on patient’s response and haematological toxicity
Men and women should use adequate contraception during and for 3 months after treatment
Reduce dose when combined with other anticancers
Anticancer medicines should only be handled by health workers trained and experienced in cytotoxic medicines