*3.2.2 Leucovorin (folinic acid)*

Leucovorin is an active metabolite of folic acid which works by enhancing enzymatic binding of 5FU onto thymidylate synthetase to prolong the half-life of 5 U and therefore potentiates the 5FU. It is not a cytotoxic agent on its own. Rarely, it can cause rash or itch.

Clinical trials compared 5FU-leucovorin regimens to 5FU-levamisole regimens and disproved the benefit of levamisole. The INT-0089 and QUASAR studies have demonstrated that there is no difference in outcome between the use of high dose or low dose leucovorin [7, 8].
