Hepatic Uptake and Intestinal Absorption of Co 58 -Labelled 5,6-dimethylbenzimidazolylcobamide Coenzyme. ∗

Abstract

Summary

Measurements of the hepatic uptake of orally administered Co⁵⁸-labelled 5,6-dibenzimidazolylcobamide coenzyme suggest that it cannot be absorbed in the intestine in the absence of intrinsic factor and, consequently, cannot be used alone in oral treatment of pernicious anemia, Under similar conditions, less coenzyme than cyanocobalamin is deposited in the liver of patients with pernicious anemia when it is orally administered with active IF preparations from animal stomach. This may be due either to the lessened effect of animal IF preparations on intestinal absorption of coenzyme or to the diminished efficiency of intestinal absorption of coenzyme as compared with that of cyanocobalamin.

Surface counting of intestinal areas after oral administration of labelled coenzyme alone and labelled cyanocobalamin to normal subjects and patients with pernicious anemia shows the radioactivity of the intestine to be much more prolonged after administration of coenzyme than after cyanocobalamin. This may be interpreted as indicating that, of the 2, coenzyme forms the easier and stronger attachment to the intestinal mucosa prior to its absorption, regardless of whether in the presence of intrinsic factor it ultimately passes through the intestinal mucosa or, in the absence of intrinsic factor, returns to the intestinal lumen.