Methotrexate

Commercial name

Metoject®, Methrexx®

Before starting treatment

Blood count, (if white blood cell count < 3 × 10⁹/L (= 3 G/L) differential blood count), liver function tests, kidney function tests, hepatitis B/C, chest X-ray as a baseline for comparison with regard to pneumonitis (if X-ray findings are abnormal: lung function tests recommended).

Administration

s.c. or p.o.

Dosage

5–15 mg/week initially, 10–30 mg/week maintenance dose, 5 mg folic acid 24–48 hours after administration
Oral: Weeks 1 and 2 – 7.5 mg; if the blood count and blood chemistry are normal after Week 2, increase to 15 mg. During the course of treatment, if response is inadequate ➝ increase to 25 mg. 5 mg folic acid 24 hours after MTX; in the event of adverse effects (gastrointestinal symptoms), an additional 5 mg folic acid before MTX. Once therapeutic efficacy has been achieved, gradually reduce the dose to the lowest effective maintenance dose.

Onset of effect

2–6 weeks

Control intervals

Blood count (if white blood cell count < 3 × 10⁹/L (= 3 G/L) differential blood count), creatinine, liver function tests, during the first month, or every 2–4 weeks if the dose is increased, then every 1–2 months, and from the 6th month onwards every 2–3 months.

Contraindications

Excessive alcohol consumption, liver disease, bone marrow disorders, kidney disease, severe, acute or chronic infections, immunodeficiency, peptic ulcer, pregnancy and breastfeeding.

Caution

Renal insufficiency (adjust dose), lung diseases, live vaccines, polypharmacy, planned conception (men and women) ➝ Counselling for women of childbearing potential regarding the risk of congenital malformations before starting treatment and mandatory contraception until 6 months after stopping treatment.

Anamnesis points, selected side effects and measures

Stomatitis, nausea, upper abdominal discomfort, diarrhoea, hair loss ➝ Reduce the dose. Gastrointestinal bleeding, infections, elevated transaminases ➝ treatment interruption. Pneumonitis ➝ discontinue treatment. In the event of an overdose: Leucovorin.

Duration of therapy

No upper limit needs to be observed. Cumulative dose is the subject of controversy: according to the literature, 1.5 g is the maximum cumulative dose. An annual FibroScan is typically recommended.