Calcium Folinate (Calcium Leucovorin): This is a reduced folate used to replenish the supply of folate metabolites depleted by methotrexate (MTX). It acts as a “rescue” therapy that, when initiated within 42 hours of high-dose MTX, allows DNA synthesis to resume by bypassing the metabolic block created by the chemotherapy
Clinical Context in Oncology
- Standard rescue after high-dose methotrexate (HD-MTX) in:
- ALL
- Osteosarcoma
- Primary CNS lymphoma
- Dose adjusted based on:
- MTX serum levels
- Time since infusion
- Renal function
Pharmacologic Pearls
- Time-sensitive: delayed initiation increases toxicity risk.
- Over-rescue may reduce MTX antitumor efficacy.
- Ineffective alone in severe MTX toxicity with markedly delayed clearance due to renal failure.
Comparison for Oncology Pharmacy Practice
| Feature | Calcium Folinate | Glucarpidase |
|---|---|---|
| Primary Function | Cellular folate rescue | Plasma MTX elimination |
| Lowers serum MTX? | ❌ No | ✅ Yes (rapidly) |
| Works intracellularly? | ✅ Yes | ❌ No |
| Role in routine HD-MTX? | Standard of care | Not routine |
| Role in MTX-induced AKI? | Supportive but insufficient alone | Definitive rescue |
| Timing sensitivity | Critical | Emergency use in delayed clearance |
| Cost | Low | Extremely high |
| Impact on MTX efficacy | Can reduce if overdosed | No direct effect on tumor intracellular MTX |
Synonyms
Calcium Leucovorin