Leucovorin Calcium (Citrovorum Factor; Folinic Acid)

A to Z Drug Facts

(loo-koe-VORE-in KAL-see-uhm)

Wellcovorin,  Lederle Leucovorin Calcium

Class: Folic acid derivative

 Action Acts as antidote to drugs that antagonize folic acid, such as methotrexate.

 Indications

Oral and parenteral: Treatment to diminish toxicity and counteract effect of overdosage of folic acid antagonists. Parenteral: Treatment of megaloblastic anemia due to folic acid deficiency when oral therapy is not feasible.

 Contraindications Pernicious anemia and other megaloblastic anemias secondary to vitamin B ₁₂ deficiency.

 Route/Dosage

Colorectal Cancer

ADULTS: IV Either 200 mg/m² followed by 5-fluorouracil (5-FU) 370 mg/m² or 20 mg/m² followed by 5-FU 425 mg/m² qd for 5 days.

Leucovorin Rescue

ADULTS: PO/IV/IM 10 mg/m² q 6 hr for 10 doses.

Megaloblastic Anemia Due to Folic Acid Deficiency

ADULTS: IV/IM 1 mg/day.

 Interactions

Barbiturates, hydantoins (eg, phenytoin), primidone: May decrease anticonvulsant activity. Fluorouracil: Enhances toxicity of fluorouracil. Methotrexate: May decrease efficacy of intrathecal methotrexate.

 Lab Test Interferences None well documented.

 Adverse Reactions

OTHER: Hypersensitivity, including anaphylaxis and urticaria. No other adverse reactions have been attributed to leucovorin alone.

 Precautions

Pregnancy: Category C. Lactation: Undetermined. Benzyl alcohol: Present in 1 mL amp and some diluents. Benzyl alcohol has been associated with fatal “gasping syndrome” in premature infants. 5-FU toxicity: Leucovorin enhances toxicity of 5-FU; dosage should be decreased. Administer only under supervision of physician experienced in use of antimetabolite cancer chemotherapy.

 Administration/Storage

• When drug is given for leucovorin rescue after high-dose methotrexate therapy, administer first dose 24 hr after beginning of methotrexate infusion.
• When drug is given as antidote for inadvertent overdosage of folic acid antagonists (eg, methotrexate), administer as soon as overdose is detected, preferably within first hour.
• Reconstitute parenteral solution using Bacteriostatic Water for Injection or Sterile Water for Injection. Bacteriostatic water mixtures must be used within 7 days; sterile water mixtures, immediately. If doses > 10 mg/m² are needed, reconstitute with Sterile Water for Injection.
• Administer IV solution slowly, at rate of < 160 mg/min, due to calcium content.
• If necessary, further dilution with 100 to 500 mL dextrose or saline solutions for intermittent infusion is possible.
• Tablets can be crushed if necessary.
• Store at room temperature and protect from light.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• Ensure that baseline laboratory values, including liver and renal function tests, CBC and platelet count, have been obtained before beginning therapy and monitor during treatment.
• Ensure that daily methotrexate levels are obtained when leucovorin is used for high-dose methotrexate rescue.
• Keep patient well hydrated. Monitor I&O carefully during treatment.

 Patient/Family Education

• Instruct patient not to double up doses, and to notify physician if dose is missed.
• Instruct patient to report the following symptoms to physician: Nausea, vomiting, diarrhea, sores in mouth, fatigue, difficulty breathing or skin disorders.
• Advise patient to notify physician if unable to keep dose down (ie, if vomiting occurs). Patient may need IM or IV therapy instead of oral medication.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
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