Abstract
Serum and urinary distributions of following oral and parenteral administration of leucovorin (3-15mg) were examined in normal adult volunteers microbiologically using Lactobacillus casei, Streptococcus faecalis and Pediococcus cerevisiae as test organisms. By the parenteral route, nearly one-third of the folate in the serum and urine was in the form of folinic acid and the remainder as 5-methyltetrahydrofolic acid. Almost all the folate in serum and urine was in the form of 5methyltetrahydrofolic acid after oral administration. Peak serum folate was observed 3hr after oral administration, later than that seen after parenteral administration (30min). Elevation of serum folate was achieved by the increase of the methyl form of folate following repeated administration of leucovorin orally and parenterally. As the form of folate actually rescuing normal cells in a high-dose methotrexate regimen was thought to be methyl, use of the oral route as a principal means of administration of leucovorin in a rescue program was looked into.
