Reversal of 5-fluorouracil-induced myelosuppression by prolonged administration of high-dose uridine.

The effect of high-dose uridine on 5-fluorouracil (5-FU)-induced toxicity was investigated. Nine patients were treated weekly with 5-FU at increasing dosages. Five patients developed dose-limiting leukopenia, and four patients developed thrombocytopenia. At dose-limiting toxicity, 5-FU treatment was repeated and followed after 3 hours by intermittent iv infusion of uridine (2 g/m2 per hr) during 72 hours. Leukopenia was reversed for several weeks but thrombocytopenia was not. Side effects consisted of mild rises in body temperature. The pharmacokinetics of uridine were similar to those observed with single-agent uridine. Our data indicate that high-dose uridine can reduce the severity of 5-FU-induced myelosuppression.