Absorption of Vitamin B 12 in a Rectal Suppository

Abstract

Summary

Absorption of Co⁵⁷-cyanocobal-amin in a rectal suppository was measured in man and rabbits by the fecal and urinary excretion test. Two extremely different doses, 10 mμg and 2,000 μg were employed in man, and 1,000' μg in rabbits. It was found that vit B₁₂ in the large dose was absorbed to a significant extent, urinary excretion being greater than after oral administration of the same dose. Absorption of the small dose of 10 mμg per rectum was negligible. The demonstrated relationship between the dose and absorption for the rectal administration has been the reverse of that for oral administration. This difference is discussed with reference to the intrinsic factor—independent absorption mechanism.