Is Methotrexate Sodium (MTX) 7.5 MG Tablet and Folic Acid (Vitamin B9) 1 MG Tablet a good combination to start with?

Methotrexate 7.5 MG with Folic Acid 1 MG is an Appropriate Starting Combination

Methotrexate 7.5 mg weekly with folic acid 1 mg daily is an appropriate starting combination for treatment, as folic acid supplementation significantly reduces methotrexate-associated toxicity without compromising efficacy. 1, 2

Methotrexate Starting Dose

• 7.5 mg weekly is a reasonable starting dose, though evidence suggests that higher initial doses (12.5-20 mg/week) may provide better efficacy without increased toxicity 1
• The British Association of Dermatologists recommends explaining to patients that:
  • Methotrexate is taken on a weekly schedule (not daily)
  • Therapeutic benefits may not be apparent for 3-12 weeks
  • Regular blood monitoring is essential 3
• For optimal results, dose escalation to 15-25 mg weekly may be considered after 4-8 weeks if clinical response is inadequate and no significant adverse effects occur 1

Folic Acid Supplementation

• 1 mg daily folic acid supplementation is strongly supported by evidence:

  • Reduces toxicity without affecting efficacy 2, 4
  • Decreases gastrointestinal side effects by 26% 5
  • Reduces risk of hepatotoxicity by 76.9% 5
  • Reduces treatment discontinuation by 60.8% 5

• Daily folic acid supplementation is preferred over intermittent dosing:

  • Does not reduce methotrexate efficacy when given daily 6
  • More cost-effective than folinic acid with similar benefits 4, 7
  • Should be taken every day except the day of methotrexate administration 1

Monitoring Requirements

• Laboratory monitoring should include:

  • Complete blood count
  • Liver function tests (ALT/AST)
  • Renal function tests (creatinine)
  • Frequency: every 1-1.5 months until stable dose, then every 1-3 months 1

• Stop methotrexate if ALT/AST increases to greater than three times the upper limit of normal 1

• Consider more frequent monitoring in patients with risk factors for hepatotoxicity:

  • Advanced age
  • Alcohol consumption
  • Hepatic dysfunction
  • Concomitant hepatotoxic medications 3, 8

Potential Drug Interactions

• Caution with NSAIDs: May reduce tubular secretion of methotrexate and enhance toxicity 8
• Avoid concomitant use with other hepatotoxic agents (e.g., azathioprine, retinoids, sulfasalazine) without close monitoring 8
• Penicillins may reduce renal clearance of methotrexate, requiring careful monitoring 8
• Oral antibiotics may decrease intestinal absorption of methotrexate 8

Common Pitfalls to Avoid

1. Dosing errors: Ensure patient understands methotrexate is taken WEEKLY, not daily
2. Inadequate monitoring: Failure to perform regular laboratory tests increases risk of undetected toxicity
3. Insufficient folic acid: Inadequate supplementation increases risk of side effects
4. Alcohol consumption: Should be limited during methotrexate therapy 3
5. Pregnancy/breastfeeding: Methotrexate is contraindicated; effective contraception is essential 3, 8

Route of Administration

• Oral administration is the preferred initial route 1
• If inadequate response or intolerance to oral methotrexate occurs, consider:
  • Split dosing
  • Switching to subcutaneous administration (higher bioavailability, fewer GI side effects) 1

In conclusion, methotrexate 7.5 mg weekly with folic acid 1 mg daily is an appropriate starting combination, though dose escalation may be needed for optimal efficacy. Regular monitoring and patient education are essential components of safe and effective therapy.