Leucovorin Injection is a chemoprotective and supportive medicine often used in cancer therapy and certain types of poisoning. It is a reduced form of folic acid (also called folinic acid), which allows it to bypass some of the steps required for folic acid activation in the body.

Here are the key details:

1. Composition and Form:

• Active ingredient: Leucovorin calcium (folinic acid).

• Supplied as a sterile solution or lyophilized powder for intravenous (IV) or intramuscular (IM) injection.

2. Mechanism of Action:

• Provides an active form of folate that participates in DNA, RNA, and protein synthesis.

• Used to “rescue” healthy cells from the toxic effects of high-dose methotrexate (an antifolate chemotherapy).

• Enhances the effectiveness of 5-fluorouracil (5-FU) by stabilizing its binding to the target enzyme (thymidylate synthase), boosting its anticancer effect.

• Acts as an antidote in folic acid antagonist toxicity (e.g., methotrexate overdose, trimethoprim, pyrimethamine).

3. Indications:

• Methotrexate rescue therapy in cancer treatment.

• Adjuvant therapy with 5-FU in colorectal and other cancers.

• Treatment of megaloblastic anemia due to folic acid deficiency (when oral therapy isn’t possible).

• Antidote in toxicities caused by folic acid antagonists.

4. Administration:

• Given by IV infusion, IV bolus, or IM injection depending on clinical need.

• Dosing depends on the indication (rescue after methotrexate, cancer therapy, or antidote use).

• Must be administered at precise timing when used with methotrexate to protect normal cells while still allowing anticancer action.

5. Side Effects:

• Generally well tolerated, but may cause:

  • Nausea, vomiting, diarrhea.

  • Mouth sores.

  • Rare allergic reactions (rash, pruritus, anaphylactoid reaction).

• When combined with 5-FU: risk of enhanced gastrointestinal and hematologic toxicities.

6. Contraindications:

• Known hypersensitivity to leucovorin or folinic acid.

• Pernicious anemia or other vitamin B12 deficiency anemias (may mask hematologic symptoms while allowing neurological damage to progress).

7. Precautions:

• Careful timing and dosing are critical in methotrexate rescue to avoid treatment failure or excess toxicity.

• Monitor blood counts, renal function, and methotrexate plasma levels (in high-dose methotrexate therapy).

• Use cautiously in patients with seizure disorders, as leucovorin may reduce the efficacy of some anticonvulsants.

8. Storage:

• Store in a cool place, protected from light.

• Reconstituted or diluted solutions should be used within the recommended stability period.