Leucovorin Calcium (Wellcovorin) — Clinical FAQs

Q: What are the most common side effects of Leucovorin Calcium?

The most commonly reported side effects of Leucovorin Calcium (≥10% incidence) include: Generally very well-tolerated, Nausea (mild), Allergic sensitization (rare), Urticaria or skin reactions (rare). Consult your oncologist for complete prescribing information.

Q: Is Leucovorin Calcium safe during pregnancy?

Leucovorin Calcium pregnancy safety: Category C — no adequate well-controlled studies. Used when clearly indicated (e.g., accidental MTX overdose in pregnancy).. Oncologists should review the complete prescribing information and discuss reproductive risks with patients before initiating therapy.

Question 1

What is Leucovorin Calcium FDA-approved to treat?

Accepted Answer

Leucovorin Calcium is FDA-approved for the following oncology indications: 1. High-dose methotrexate rescue — prevention and treatment of methotrexate toxicity after high-dose MTX therapy in osteosarcoma and other malignancies 2. Biochemical modulation of fluorouracil (5-FU) in colorectal cancer — combination with 5-FU as part of FOLFOX, FOLFIRI, and FOLFOXIRI regimens 3. Megaloblastic anemia due to folate deficiency (when oral folic acid not feasible) 4. Treatment of accidental folic acid antagonist overdose (methotrexate, trimethoprim, pyrimethamine).

Question 2

How does Leucovorin Calcium work (mechanism of action)?

Accepted Answer

Leucovorin (folinic acid; 5-formyltetrahydrofolate) is a reduced, bioactive form of folic acid that does not require dihydrofolate reductase (DHFR) activation. It serves two distinct roles in oncology: (1) Methotrexate rescue: leucovorin bypasses the DHFR inhibition imposed by methotrexate, restoring the intracellular reduced folate pool (particularly 5,10-methyleneTHF and 10-formylTHF) needed for thymidylate and purine synthesis in normal tissues (bone marrow, GI mucosa) — thereby reversing methotrexate toxicity without meaningfully reducing anti-tumor activity (tumor cells are preferentially killed by MTX due to impaired leucovorin transport and polyglutamylation). (2) 5-FU biochemical modulation: leucovorin stabilizes the ternary inhibitory complex formed between thymidylate synthase (TS), the 5-FU catabolite FdUMP (fluorodeoxyuridine monophosphate), and 5,10-methyleneTHF — prolonging and deepening TS inhibition, significantly enhancing 5-FU cytotoxicity. This modulation increases 5-FU response rates in colorectal cancer by ~50% compared to 5-FU alone.

Question 3

How is Leucovorin Calcium administered?

Accepted Answer

Leucovorin Calcium is administered Intravenous (IV) or Oral (PO) or Intramuscular (IM). MTX rescue: IV leucovorin 15–25 mg/m² every 6 h starting 24 h after the beginning of MTX infusion; continue based on serum MTX levels until MTX <0.

Question 4

What are the most common side effects of Leucovorin Calcium?

Accepted Answer

The most commonly reported side effects of Leucovorin Calcium (≥10% incidence) include: Generally very well-tolerated, Nausea (mild), Allergic sensitization (rare), Urticaria or skin reactions (rare). Consult your oncologist for complete prescribing information.

Question 5

Is Leucovorin Calcium safe during pregnancy?

Accepted Answer

Leucovorin Calcium pregnancy safety: Category C — no adequate well-controlled studies. Used when clearly indicated (e.g., accidental MTX overdose in pregnancy).. Oncologists should review the complete prescribing information and discuss reproductive risks with patients before initiating therapy.

Leucovorin Calcium — Drug Monograph

Mechanism of Action

FDA Indications

Common Side Effects

Clinical Pearl

Related Therapies & Mechanisms