What is the proper way to take methotrexate (MTX)?

Proper Administration of Methotrexate

Methotrexate should be taken once weekly (not daily) on the same day each week, with folic acid supplementation to reduce toxicity, and requires regular blood monitoring to ensure safety. 1

Dosing Schedule and Administration

• Weekly dosing: Methotrexate must be taken ONCE WEEKLY, not daily. This is critical as daily dosing can lead to fatal toxicity 1
• Starting dose: In healthy adults, begin with 5-15 mg weekly 1
• Dose titration: Dose can be gradually increased if needed, up to a maximum of 25 mg weekly 1
• Administration route:
  • Oral tablets are preferred for initial treatment (absorption is rapid and effective) 2
  • Subcutaneous injection may be considered if oral therapy fails due to inadequate response or intolerance 3
• Timing: Take on the same day each week to establish a routine and prevent missed doses 1

Required Supplementation

• Folic acid: Must be taken to reduce toxicity (strong recommendation, Grade A evidence) 1
• Typically prescribed as 5 mg weekly (taken 24-48 hours after methotrexate) or 1 mg daily (except on methotrexate day) 4

Monitoring Requirements

• Initial monitoring: Blood tests (FBC, LFTs, U&E) every 7-14 days for the first month 1
• Ongoing monitoring: Once therapy is stabilized, blood tests every 2-3 months 1
• Liver monitoring: For patients with psoriasis, PIIINP (a marker of liver fibrosis) should be checked every 3 months 1

Important Precautions

• Alcohol limitation: Restrict alcohol intake as it increases risk of hepatotoxicity 1
• Pregnancy: Absolutely contraindicated during pregnancy and effective contraception is essential 1
• Drug interactions: Many medications can increase methotrexate toxicity, including:
  • NSAIDs (including aspirin)
  • Certain antibiotics (penicillins, tetracyclines, sulfonamides)
  • Proton pump inhibitors
  • Statins 1

Warning Signs Requiring Medical Attention

Patients should seek urgent medical care if they develop:

• Fever or flu-like symptoms
• Mouth ulceration
• Unusual fatigue
• Unexplained bruising or bleeding
• Nausea, vomiting, abdominal pain, or dark urine
• Breathlessness or cough 1

Common Pitfalls to Avoid

1. Dosing confusion: Methotrexate tablets come in 2.5 mg and 10 mg strengths that look similar. To avoid confusion, it's recommended to prescribe only the 2.5 mg strength 1

2. Daily vs. weekly dosing: The most dangerous error is taking methotrexate daily instead of weekly. Always emphasize the WEEKLY schedule 1

3. Inadequate monitoring: Patients unable to comply with regular blood monitoring should not receive methotrexate 1

4. Overdose risk: Symptoms of overdose may take 6-23 days to manifest and can be life-threatening. Early treatment with folinic acid is essential 1

5. Premature discontinuation: Therapeutic benefit may not be apparent for 3-12 weeks, so patients should continue treatment for at least 12-16 weeks before determining efficacy 1

By following these guidelines, patients can maximize the benefits of methotrexate therapy while minimizing potential risks.