VITAMIN B12 INJECTION
Each 2 mL contains: 1000 micrograms (1 mg) Cyanocobalamin
Cyanocobalamin is involved by way of its participation in the
formation and metabolism of purines and pyrimidines, in the
synthesis of nucleoproteins, and thus in the maintenance of normal
Vitamin B12 substances bind to intrinsic factor and are then actively absorbed
from the gastro-intestinal tract. Absorption is impaired in
patients with an absence of intrinsic factor. Absorption from the
gastro-intestinal tract can also occur by passive diffusion.
Vitamin B12 is extensively bound to specific plasma proteins called
transcobalamins; transcobalamin II appears to be involved in the
rapid transport of the cobalamins to tissues. It is stored in the
liver, excreted in the bile and undergoes extensive enterohepatic
recycling; part of an administered dose is excreted in the urine,
most of it in the first 8 hours; urinary excretion, however,
accounts for only a small fraction in the reduction of total body
stores acquired by dietary means. Vitamin B12 diffuses across the placenta and also appears in breast milk.
Indicated in vitamin B12 deficiencies manifested by megaloblastic anaemia and neurological
conditions. Pernicious anaemia and its neurological complication,
subacute combined degeneration of the spinal cord. Macrocytic
anaemias associated with nutritional deficiencies. Intestinal
malabsorption, megaloblastosis, diet-related deficiency,
post-gastrectomy. Indications for prophylaxis include strict
vegetarianism, post-gastrectomy, and ileal resection and conditions
of the small intestine that would predictably cause deficiency.
Cyanocobalamin should not be given before a diagnosis has been
fully established because of the possibility of masking symptoms of
subacute degeneration of the spinal cord. Cyanocobalamin should not
be used to treat megaloblastic anaemia of pregnancy. Cyanocobalamin
should not be administered before pernicious anaemia or folic acid
deficiency has been ruled out.
Must not be administered intravenously.
DOSAGE AND DIRECTIONS FOR USE:
In the absence of neurological involvement, cyanocobalamin may be
administered in doses of 250 to 1000 micrograms intramuscularly on
alternate days for 1 to 2 weeks, then 250 micrograms weekly until
the blood count returns to normal. Maintenance doses of 1000
micrograms are administered monthly.
If there is neurological involvement, cyanocobalamin may be given
in doses of 1000 micrograms on alternate days and continued for as
long as improvement occurs.
For the prophylaxis of anaemia associated with vitamin B12 deficiency resulting from gastrectomy or malabsorption syndromes
cyanocobalamin may be given in doses of 250 to 1000 micrograms
intramuscularly each month.
SIDE EFFECTS AND SPECIAL PRECAUTIONS:
Allergic reactions have been reported after injection.
Vitamin B12 should be given prophylactically only when there is a reasonable
indication. Dietary deficiency in the strict vegetarian, the
predictable malabsorption of vitamin B12 in patients who have had a gastrectomy, and certain diseases of
the small intestine constitute such indications.
Protect from light. Store below 25°C.
Keep out of reach of children.