Main indication in lupus

Methotrexate does not have market authorisation for lupus, but experts recognize an effectiveness in lupus with severe joint / cutaneous involvement or with serous involvement (pleuritis, pericarditis).

Dosage

- In general 7.5 to 25 mg / week depending on the clinical manifestations

- Usual maximum dose: 0.3 mg/kg/week. 2.5 mg tablets; intramuscular doses of 2.5 mg, 10 mg; syringes for subcutaneous injection

- Orally (in 1 to 3 doses over 24 hours), intravenous, intramuscular, subcutaneous

Main drug interactions warranting particular caution

- Nonsteroidal anti-inflammatory drugs, antifungals

- Antivitamin K, trimethoprime/sulfamethoxazole, anticonvulsants

Main side effects

- Cytopenia, agranulocytosis (significant decrease in white blood cells)

- Nausea, pain, vomiting, canker sores (aphthous ulcers)

- Pneumonitis (lung involvement) of hypersensitivity, hepatic cytolysis

- Community and opportunistic infections: pneumocystosis (especially if lymphopenia)

- Hair loss (alopecia)

Contraindications

- Pregnancy and lactation

- Hypersensitivity to treatment

- Severe hepatocellular insufficiency and excessive alcohol intake

- Severe renal failure

- Anaemia, thrombocytopenia, neutropenia, lymphopenia

- Infections (temporary discontinuation of treatment)

Precautions for use

- Effective contraception up to 3 months after stopping treatment

- In combination with intake of folic acid reduces the frequency of minor side effects: 5 mg/week (10 mg/week if methotrexate >20 mg/week), 48 hours after methotrexate

Monitoring

- Blood count, creatinine, transaminases, alkaline phosphatases, gamma-GT: 1/week for 1 month, then 1/15 days for 2 months, and then 1/month

- Dose reduction if transaminases higher than normal or neutrophils <1000/mm³ or lymphocytes <500/mm³

- Clinical monitoring: infection, pulmonary auscultation