Hypersensitivity

anaphylactic shock and death Cardiovascular - Pulmonary edema, congestive heart failure early in treatment, peripheal vascular thrombosis

Dermatologic: Itching, transsitory exanthema

Misceallaneous: Feeling of swelling of the entire body, mild transient diarrhea, polycythemia vera, pain at injection site, severe and swift optic nerve atrophy

Hypersensitivity to cobalt, vitamin B12 or any other component of these products

Special precautions: Inadequate response- Parentral administration is preferred for pernicious anemia. Avoid the IV route A blunted or impeded therapeutic response may be due to infection, uremia, bone marrow suppressant drugs (eg. chloramphenicol), concurrent iron or folic acid deficiency

Vitamin B12 defiency- allowed to progress for > 3 months may produce permanent degenerative lesions of the spinal cord

Optic nerve atrophy- Patients with early Lebers disease (heriditary optic nerve atrophy) treated with cyanocobalamin suffer severe and swift optic atrophy. Hypokalemia and sudden death occur in severe megaloblastic anemia which is treated intensely

Benzyl alcohol- some of these products contain benzyl alcohol, which has been associated with fatal gasping syndrome in prematutre infants.

Pregnancy: Adequate and well controlled studies have not been performed in pregnant woman. However B12 is an essential vitamin and needs are increased during pregnancy. The national Academy of Sciences has recommended that 2.2mcg/day should be consumed during pregnancy

Lactation: Vitamin B12 excreted in breast milk in concentrations that approximate the mothers Vitamin B12 blood level. Amounts recommended by the Food and Nutrition Board, National Acadeemy of seiences- National research Council (2.6mcg daily) should be consumed during lactation.

Children: The Food and Nutrition Board , National Academy of Sciences., National Research Council recommend a daily intake of 0.3 to 0.5mcg/day for infants < 1 year ofage and 0.7 to 1.4mcg/day for children 1 to 10 years

Dosage-

Recommended dose is 30cmg/day for 5 to 10 days followed by 100 to 200mcg monthly Children may be given a otal of 1 to 5mg over 2 or more weeks in dfoses of 100mcg then 30 to 50mcg every 4 weeks for maintenance

Missed dose :

1. If you miss taking a vitamin for 1 or more days there is no cause for concern, since it takes some time for your body to become seriously low in vitamins

2. However, if your health care professional has recommended that you take this vitamin, try to remember to take it as directed every day.

Pharmacology

Vitamin B12 (cyanocobalamin and hydroxycobalamin ) is essential to growth, cell reproduction, hematopoiesis, and nucleoprotein and myelin synthesis. Its physiologic role is associated with methylation, participitating in nucleic aid and protein synthesis..

Cyanocobalamin participitates in red blood cell formation through activation of folic acid coenzymes. Cyanocobolamin has hematopietic activities apparently identical to that of the anti-anemia factor in purified liver extract.

Pharmacokinetics:

Absorption of vitamin B12 depends on the presence of sufficient intrinsic factor and calcium. Cyanocobalamin is rapidly absorbed from IM and SC injection sites. the plasma level peaks within 1 hour.

Once absorbed it is bound to plasma proteins, stored mainly in the liver, and is slowly released when needed to carry out mormal cellular metabolic functions. Within 48 hours after injection, 50% to 98% ofvthe dose appears in the urine.

Pregnancy:

Adequate and well controlled studies have not been performed in pregnant woman. However B12 is an essential vitamin and needs are increased during pregnancy. The national Academy of Sciences has recommended that 2.2mcg/day should be consumed during pregnancy

Lactation:

Viatmin B12 excreted in breast milk in concentrations that approximate the mothers Vitamin B12 blood level. Amounts recommended by the Food and Nutrition Board, National Acadeemy of seciences- National research Council (2.6mcg daily) should be consumed during lactation.

Children: The Food and Nutrition Board , National Academy of Sciences., National Research Council recommend a daily intake of 0.3 to 0.5mcg/day for infants < 1 year ofage and 0.7 to 1.4mcg/day for children 1 to 10 years