Leucovorin

Indications

Leucovorin is used for: Methotrexate Overdose, Methanol Poisoning, Trimethoprim Toxicity

Adult Dose

Methotrexate Overdose 1:1 ratio for leucovorin to inadvertent methotrexate overdose, within 1 hr Initial IV, then may switch to IM q6hr and continue until methotrexate level has fallen below 0.05 micromolar and the renal failure has resolved High Dose Methotrexate Rescue 10 mg/m² IV q6hr starting 24 hr after methotrexate May give PO after 1st IV dose Methanol Poisoning 1 mg/kg (50-70 mg adults) IV q4-6hr Trimethoprim Toxicity 10 mg/m² PO q6hr

Child Dose

Renal Dose

Administration

IV Preparation Reconstitute w/ BWI or SWI of 10 mg/mL or 20 mg/mL (for 350 mg vial) Available in 10 mg/mL preservative-free solutions Do not use benzyl alcohol-containing diluents for doses >10 mg/sq.meter Reconstituted solution is stable for 7 d Use immediately if reconstituted w/ preservative-free solution IV/IM Administration Infusion: not to exceed 160 mg/min

Contra Indications

Vitamin B12 deficiency anemia and pernicious anemia

Precautions

Hypersensitivity reactions including anaphylactoid reactions & urticaria Risk of severe neurological complications in patients with undiagnosed anemia Geriatric or debilitated patients receiving cotreatment with fluorouracil May increase tosicity of 5-fluorouracil May increase treatment failure of sulfamethoxazole-trimethoprim therapies Formulations containing benzyl alcohol not to be used in infants Thrombocytosis reported during intra-arterial infusion of methotrexate

Pregnancy-Lactation

Pregnancy Category: C Lactation: not known whether distributed in breast milk; use caution

Interactions

Side Effects

Side effects of Leucovorin : Frequency Not Defined Diarrhea Nausea Vomiting Stomatitis Thrombocytosis Anaphylactoid reaction Wheezing Urticaria Anaphylactoid reactions

Mode of Action

Serves as a cofactor supplement to counteract folic acid antagonists such as methotrexate; leucovorin is an active metabolite of folic acid Displaces methotrexate from intracellular binding sites and restores the folate required for DNA/RNA synthesis In methanol toxicity it serves as a tetrahydrofolate source to help the body eliminate the formic acid resulting from methanol's toxicity