Drug reference

leucovorin calcium

Vitamin B9 derivative · Antidote

Vitamin B9 derivativeAntidote

CDSCO approved

EXCRETION

—

not curated

INTERACTIONS

—

none in our sources

PREGNANCY

—

not curated

Mechanism

Leucovorin calcium is the 5-formyl derivative of tetrahydrofolic acid (folinic acid). It acts to circumvent the inhibition of dihydrofolate reductase by drugs like methotrexate, by providing a reduced folate that bypasses the blocked enzymatic step. In colorectal cancer, it potentiates the effect of 5-fluorouracil by binding and stabilizing 5-dUMP and thymidylate synthetase.

Indications

rescue agent after high-dose methotrexatetreatment of advanced colorectal cancer (with fluorouracil)megaloblastic anemias due to folic acid deficiency when oral therapy is not feasibleantidote to counteract toxicity of folate antagonists (e.g., pyrimethamine or trimethoprim)

Dosing

Adult: Starting 24 h after methotrexate treatment to replenish active folate stores. For colon cancer, it potentiates the effect of 5-fluorouracil. Dosing not explicitly quantified beyond these general statements.