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Studies on Vitamin B 12 Retention Comparison of Retention Following Intramuscular Injection of Cyanocobalamin and Hydroxocobalamin
Author(s) -
Hertz Henrik,
Kristensen H. P. Østergaard,
HoffJØrgensen E.
Publication year - 1964
Publication title -
scandinavian journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.904
H-Index - 84
eISSN - 1600-0609
pISSN - 0036-553X
DOI - 10.1111/j.1600-0609.1964.tb00001.x
Subject(s) - hydroxocobalamin , cyanocobalamin , chemistry , vitamin b , cellophane , urine , vitamin , vitamin b12 , biochemistry , organic chemistry
While according to recent investigations cyanocobalamin (CN‐B 12 ), so far the most commonly used vitamin B 12 preparation, must be considered an “artificial product”, hydroxocobalamin (OH‐B 12 ) is probably one of the forms of vitamin B 12 which occurs naturally in the animal organism. The main object of the present study was to elucidate the difference in retention following intramuscular injection of CN‐B 12 and OH‐B 12 , among other things with a view to the applicability of OH‐B 12 in the treatment of pernicious anaemia. After i. m. injection of about 1 mg CN‐B 12 and OH‐B 12 , normal subjects excreted within 24 hours about 80 per cent and about 25 per cent, respectively, in the urine. This corresponds a retention of about 20 per cent CN‐B 12 compared with about 75 per cent OH‐B 12 . The serum concentrations about 1 hour after the injection were approximately the same whether CN‐B 12 or OH‐B 12 was given. Thereafter, the concentration of CN‐B 12 fell far more rapidly than that of OH‐B 12 , so that during the subsequent 48 hours the OH‐B 12 concentration was 3–6 times higher than the CN‐B 12 concentration. Dialysis experiments showed that OH‐B 12 passes far more slowly through a cellophane membrane than does CN‐B 12 , and that OH‐B 12 is bound to the serum proteins in far greater quantities than is CN‐B 12 . The amount of bound, i. e. non‐dialysable, CN‐B 12 increased only slightly with increasing total concentration, while the amount of bound OH‐B 12 increased proportionally, making up about two‐thirds of the total concentration. These two factors – greater binding to the serum proteins and slower diffusion of non‐bound OH‐B 12 – reduce glomerular filtration and must be considered the main explanation why far less of injected OH‐B 12 than of injected CN‐B 12 is lost in the urine. It is concluded that owing to its excellent retention in the organism – without addition of absorption‐retarding substances – hydroxocobalamin (OH‐B 12 ) must be particularly suited for the treatment of pernicious anaemia and other B 12 deficiencies, all the more so as OH‐B 12 is presumably a physiological vitamin B 12 . In maintenance therapy, 1 mg hydroxocobalamin i. m. every 3 months should be sufficient.