Antimetabolite (Ectopic Pregnancy Management) Pregnancy: X — teratogenic; contraception required for 3 months post-treatment

Methotrexate (Ectopic)

Brand names: Methofar, Methotrexate Injection

Adult dose

Dose: Single-dose: 50mg/m² IM. Two-dose: 50mg/m² IM on days 0 and 4

Route: IM

Frequency: Single dose or two-dose protocol

Monitor hCG on day 4 and day 7. Adequate response: ≥15% fall in hCG between days 4 and 7. Multi-dose: 1mg/kg IM on days 1,3,5,7 alternating with folinic acid rescue.

Clinical pearls

Haemodynamically stable ectopic ONLY — ruptured ectopic requires emergency surgery
Administer in outpatient setting only if strict criteria met: hCG <3000 IU/L, no fetal cardiac activity, adherent patient
Abdominal pain days 3–7 is NORMAL (tubal separation) — distinguish from rupture
AVOID NSAIDs during treatment — significantly increase toxicity and may impair treatment
Contraception for 3 months after treatment — teratogenic
Folinic acid NOT given in ectopic protocol (unlike rheumatology use) — it reverses treatment effect

Contraindications

Ruptured ectopic (surgical emergency)
Heterotopic pregnancy
Hepatic/renal impairment
Immunodeficiency
Pre-existing blood dyscrasias
Peptic ulcer disease
Breastfeeding

Side effects

Nausea, vomiting
Mucositis
Bone marrow suppression
Hepatotoxicity
Pneumonitis
Abdominal pain (first 3–4 days — normal)
Photosensitivity

Interactions

NSAIDs — significantly increase methotrexate toxicity (bone marrow suppression)
Co-trimoxazole/trimethoprim — folate antagonism increases toxicity
Alcohol — additive hepatotoxicity

Monitoring

hCG on days 4 and 7 (key monitoring), then weekly until <5 IU/L
FBC before treatment
LFTs and creatinine before treatment
Pain (distinguish normal from rupture)
Vital signs (rupture risk)

Reference: RCOG Ectopic Pregnancy Green-top Guideline 2016; NICE NG126. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways