Examples

Leucovorin comes in intravenous (IV), intramuscular (IM) injection (shot), and oral form.

How It Works

Leucovorin is a derivative of folic acid. Leucovorin works differently depending on whether it is used with methotrexate (MTX) or fluorouracil (5-FU).

• Methotrexate: Leucovorin is given to "rescue" the gastrointestinal lining and bone marrow cells from MTX toxicity. Most of the complications and side effects of methotrexate can be either prevented or treated by using leucovorin, which is usually given 24 hours after methotrexate.
• Fluorouracil: Leucovorin increases the effectiveness of 5-FU, increasing the anticancer effect.

Why It Is Used

Leucovorin is used with either methotrexate (MTX) for the treatment of ectopic pregnancy or fluorouracil (5-FU) for colon or breast cancer.

How Well It Works

Most of the complications and side effects of methotrexate can be either prevented or treated by using leucovorin, which is usually given 24 hours after the methotrexate is given.

Leucovorin enhances the binding of fluorouracil (5-FU) and prolongs the life span of 5-FU, increasing the anticancer effect.¹

Side Effects

Leucovorin is very well tolerated and has almost no side effects of its own.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Leucovorin generally decreases the severity of side effects of MTX. It can increase the severity of the side effects of 5-FU when used with that medication.

Leucovorin should be administered only under the supervision of a medical oncologist.

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References

Citations

1. Meyerhardt JA, Mayer RJ (2005). Systemic therapy for colorectal cancer. New England Journal of Medicine, 352(5): 476–486.