Hydroxocobalamin. II. Absorption from the Site of Injection and Uptake by the Liver and Calf Muscle in Man

Abstract

Labeled hydroxocobalamin, administered intramuscularly in man, is absorbed more slowly from the site of injection and deposited in the liver and calf muscle to a degree equal to or higher than that of cyanocobalamin at an equivalent dose. These findings, together with those reported in Part I of this paper, suggest the applicability of hydroxocobalamin as a long-acting vitamin B12 in man. These conclusions, however, require the support to be obtained from long-range observations on patients with vitamin B12 depletion.

The Plasma Disappearance of Radioactive Cyanocobalamin: Effect of Prior Administration of Vitamin B12 Analogues

“…An alternative or perhaps additional explanation may be in the retention of intramuscularly administered vitamins B12 at the injection site. There is evidence to indicate that hydroxocobalamin is retained at the injection site for a more prolonged period than cyanocobalamin (Glass, Lee and Hardy, 1961). Twentyfour hours after injection, the percentage difference is small-perhaps 2 or 3 per cent.…”

Vitamin B12status in health and disease: a critical review. Diagnosis of deficiency and insufficiency – clinical and laboratory pitfalls

“…Hydroxocobalamin is retained far more efficiently than cyanocobalamin. It disperses more slowly from the injection site, binds more strongly to plasma, and has a slower diffusion rate than cyanocobalamin [230][231][232]. Hence, cyanocobalamin is administered at 1000 mg once a month, while the same dose of hydroxocobalamin can be administered every two to three months.…”