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