American Journal of Clinical Nutrition, Vol 10, 480-483, Copyright © 1962 by The American Society for Clinical Nutrition, Inc.

Parenteral Studies with Vitamin B₁₂ Complexes

¹ From the Home for the Jewish Aged, Philadelphia, Pennsylvania, and Merck Sharp & Dohme Research Laboratories, West Point, Pennsylvania

Thirty healthy, noninstitutionalized volunteer subjects were divided into three groups and given an intramuscular dose of 1 mg. of either cyanocobalamin, hydroxocobalamin or coenzyme vitamin B₁₂. Serum vitamin B₁₂ was measured over a four week period and urinary excretion was followed quantitatively for seventy-two hours and qualitatively for the duration of the study period.

The group receiving hydroxocobalamin maintained statistically significant higher serum levels over the period of the study, with a slower rate of urinary excretion than those receiving either cyanocobalamin or coenzyme vitamin B₁₂.

The total urinary excretion over a seventy-two hour period was much greater in the group receiving cyanocobalamin than in either of the other two groups. The low total recovery of coenzyme vitamin B₁₂ in the absence of sustained elevation of serum levels is paradoxical and may be due to the instability of the compound or to tissue retention, but, at the moment, it is unexplained.