Comparative Absorption of Vit. B 12 Analogues by Normal Humans. III. 5,6-Dichlorobenzimidazole,5,6-Desdimethylbenzimidazole and 5-Hydroxybenzimidazole Analogues

Summary

1. Urinary excretion tests of oral absorption were performed in normal humans with Co⁶⁰-labeled 5,6-dichlorobenzimidazole, 5,6-desdimethylbenzimidazole and 5-hydroxybenzimidazole analogues of vitamin B₁₂. 2. Excretion responses obtained with desdimethyl- and hydroxybenzimidazole derivatives are exceedingly low, indicating but slight oral absorption. 3. Behavior of labeled dichlorobenzimidazole analogue indicates good absorption, approximating one-half that of cyanocobalamin. In this case, maximal excretion is attained after flushing injections with unlabeled homologous compound.