American Journal of Clinical Nutrition, Vol 8, 214-217, Copyright © 1960 by The American Society for Clinical Nutrition, Inc.

Serum Levels of Vitamin B₁₂ Following Intramuscular Injection of a Depot Preparation

¹ From the Sterling-Winthrop Research Institute, Renssclaer, New York

Serum levels of vitamin B₁₂ were determined in two groups of four dogs each following the intramuscular administration of vitamin B₁₂ in water or in a depot oil and aluminum monosterate preparation.

Confirming earlier published observations based on the urinary excretion of the vitamin following its administration in each of these vehicles, the studies with the dogs showed that the vitamin administered in a depot form maintained elevated levels for a period about three times that following the administration of the vitamin in the usual aqueous medium.

It was noted, in addition, that the serum levels which followed the administration of the vitamin in the depot preparation were two to three times those which followed the administration of the vitamin in water.

Tolerance to injection of the preparation was established. No untoward blood or tissue effects were seen in dogs or monkeys following forty-six injections of the preparation over a 170-day period.

Accordingly, it is clear that administration of vitamin B₁₂ in oil with aluminum monosterate results in prolonged and elevated serum levels of vitamin B₁₂.