Hydroxocobalamin : IV. Biological Half-Life of Hydroxocobalamin in the Human Liver

The mean hepatic biological half-life of Co⁵⁷-hydroxocobalamin injected to 5 normal human subjects was similar to that of Co⁶⁰-cyanocobalamin, as shown by double-label hepatic surface counting during the first 30 weeks after intramuscular or intravenous injection of cobalamins. In 2 cases in whom the counting was extended over a year’s period, the clearance of hepatic radioactivity following the intramuscular injection of hydroxocobalamin has slowed down as compared to that of cyanocobalamin, between the 30th and 52nd week after injection.