Folinic Acid (Leucovorin) Dosing for a 91-Pound Patient
For a patient weighing 91 pounds (41.3 kg), the appropriate dose of folinic acid (leucovorin) is 10-20 mg three times weekly when used as a supplement with methotrexate therapy.
Dosing Guidelines Based on Clinical Context
Methotrexate Therapy
- For patients receiving methotrexate as part of chemotherapy regimens (such as FOLFOX or FOLFIRI), leucovorin is dosed at 400 mg/m² IV over 2 hours on day 1 1
- For prevention of methotrexate toxicity, folinic acid supplementation at 10-20 mg three times weekly is recommended 1, 2
- For patients with significant methotrexate toxicity, higher rescue doses may be required based on methotrexate levels 2, 3
Dietary Deficiency or Chronic Conditions
- For treatment of folate deficiency, 1-5 mg of folinic acid daily is recommended 1
- For patients on chronic hemodialysis, 1-5 mg daily or 1 mg after each dialysis session is sufficient to maintain therapeutic folate levels 1, 4
Toxoplasmosis Treatment
- For children with toxoplasmosis, 10-20 mg three times weekly is recommended when used alongside pyrimethamine 1
Weight-Based Considerations
- For a 91-pound (41.3 kg) patient:
- If calculating based on body surface area (BSA), first convert to BSA using standard formulas (approximately 1.3 m² for this weight)
- For chemotherapy protocols, the dose would be approximately 520 mg (400 mg/m² × 1.3 m²) 1
- For supplementation with methotrexate therapy, the standard 10-20 mg three times weekly is appropriate regardless of weight 1, 2
Administration Routes
- Oral administration is preferred for long-term supplementation 1
- Intravenous administration is used in chemotherapy protocols 1
- In cases where oral treatment is ineffective or not tolerated, subcutaneous, IV, or IM administration at 0.1 mg/day can be considered 1
Monitoring and Adjustments
- Monitor complete blood count, liver function, and renal function regularly during therapy 2
- For patients with renal insufficiency, dose adjustments may be necessary as both methotrexate and folinic acid are primarily excreted by the kidneys 2, 3
- Measure folate status in plasma or serum (for short-term status) or RBC (for long-term status) using validated methods 1
Common Pitfalls to Avoid
- Do not confuse folinic acid (leucovorin) with folic acid, as they have different metabolic pathways and clinical applications 1, 5
- Leucovorin does not require the same metabolic conversion as folic acid and may be more bioavailable 5
- When using l-leucovorin instead of d,l-leucovorin, the dose should be reduced by half as only the l-isomer is pharmacologically active 6
- Excessive folic acid supplementation (>5 mg/day) may mask vitamin B12 deficiency 1