Leucovorin

Leucovorin is frequently used in conjunction with Methotrexate and 5-FU. Leucovorin is not a Chemotherapeutic drug itself, however it is an adjunct to these chemotherapy drugs. Leucovorin is a compound similar to Folic acid, which is a vital Vitamin. Leucovorin has been around and in use for many decades. The mechanism of action of this drug is quite interesting and is very different when combined with Methotrexate as opposed to 5-FU.

Leucovorin Rescue for Methotrexate Toxicity

Methotrexate exerts its Chemotherapeutic effect by its ability to counteract and compete with folic acid in cancer cells resulting in folic acid deficiency within the cells and causing their demise. Normal cells are not immune form this effect of Methotrexate either. As a result, it can cause significant side effects in the body, such as:

Low white blood counts
Low platelet count
Anemia
Hair Loss
Soreness of the mouth, difficulty swallowing
Diarrhea
Liver damage
Lung damage
Nerve damage
Kidney damage

Most of these complications and side effects of Methotrexate can be either prevented or treated by using Leucovorin which is normally administered 24 hours after the Methotrexate is given. This will allow the Methotrexate to exert its anti cancer effect.

Leucovorin comes in intravenous as well as oral tablets. Intravenous form of Leucovorin is used when an immediate effect is needed and in cases of severe Methotrexate toxicity. Tablets are used every six hours for 48 hours for purpose of preventing the side effects.

5-FU and Leucovorin:

5-FU is normally administered by intravenous route. The life span of 5-FU in blood and body tissues is very short and limited to minutes. 5-FU binds to an enzyme inside of the cancer cells called Thymidilate Synthetase and thereby exerts its anti cancer effect on the cells. Leucovorin enhances the binding of 5-FU to this enzyme and as a result prolongs the life span of 5-FU, resulting in a greater anti cancer effect.

Side effects of Leucovorin:

This drug is very well tolerated and has almost no side effects of its own. When used in conjunction with 5-FU it can also increase the severity of side effects of that drug.