Bioequivalence of two leucovorin calcium tablet formulations.

In a randomized, single-dose, two-way crossover study, 36 male volunteers received 25 mg each of two oral formulations of leucovorin calcium. Reduced serum folate concentrations were determined over the 24 hours after dosing. There were no statistically significant differences in areas under the serum concentration-time curves for total L-tetrahydrofolates, L-leucovorin (L-5-formyltetrahydrofolate), and L-5-methyltetrahydrofolate (the active metabolite of leucovorin and the predominant circulating form of reduced folate after oral administration). The peak serum concentrations and times to peak serum concentrations were also not significantly different. We conclude that the two leucovorin calcium 5 mg tablet formulations are bioequivalent.