Anacobin , Bedoz , Nascobal, Rubion
Classifications: vitamin b12 ; Therapeutic: vitamin b12
Pregnancy Category: A (PO or nasal spray); C (parenteral)
25 mcg, 50 mcg, 100 mcg, 250 mcg tablets; 400 mcg/unit, 500 mcg/0.1 mL nasal gel; 500 mcg/0.1 mL nasal spray
Vitamin B12 is a cobalt-containing b complex vitamin produced by Streptomyces griseus. Essential for normal growth, cell reproduction, maturation of RBCs, nucleoprotein synthesis, maintenance of nervous system
(myelin synthesis), and believed to be involved in protein and carbohydrate metabolism. Vitamin B12 deficiency results in megaloblastic anemia, dysfunction of spinal cord with paralysis, GI lesions.
Therapeutically effective for treatment of vitamin B12 deficiency and pernicious anemia.
Vitamin B12 deficiency due to malabsorption syndrome as in pernicious (Addison's) anemia, sprue; GI pathology, dysfunction, or surgery;
fish tapeworm infestation, and gluten enteropathy. Also used in B12 deficiency caused by increased physiologic requirements or inadequate dietary intake, and in vitamin B12 absorption (Schilling) test.
To prevent and treat toxicity associated with sodium nitroprusside.
History of sensitivity to vitamin B12, other cobalamins, or cobalt; early Leber's disease (hereditary optic nerve atrophy), indiscriminate use in folic acid
deficiency; pregnancy [category A, category C (parenteral)].
Heart disease, anemia, pulmonary disease.
Route & Dosage
|Vitamin B12 Deficiency
Adult: IM/Deep SC 30 mcg/d for 510 d, then 100200 mcg/mo
Child: IM/Deep SC 100 mcg doses to a total of 15 mg over 2 wk, then 60 mcg/mo
Adult: IM/Deep SC 1001000 mcg/d for 23 wk, then 1001000 mcg q24wk Intranasal one pump in one nostril once weekly
Child: IM 3050 mcg/d x 2 wk to total of 1000 mcg, then 100 mcg/mo
Infant: IM 1000 mcg/d x at least 2 wk, then 50 mcg/mo
Diagnosis of Megaloblastic Anemia
Adult: IM/Deep SC 1 mcg/d for 10 d while maintaining a low folate and vitamin B12 diet
Adult: IM/Deep SC 1000 mcg times 1 dose
Adult: PO 125 mcg/d
Child: PO <1 y, 0.3 mcg/d; ≥1 y, 1 mcg/d
- PO preparations may be mixed with fruit juices. However, administer promptly since ascorbic acid affects the stability of
- Administration of oral vitamin B12 with meals increases its absorption.
- Give deep SC by slightly tenting the skin at the injection site.
- IM may be given into any normal IM injection site.
- Preserved in light-resistant containers at room temperature preferably at 15°30° C (59°86°
F) unless otherwise directed by manufacturer.
Adverse Effects (≥1%) Body as a Whole:
Feeling of swelling of body, anaphylactic shock, sudden death. CV:
Peripheral vascular thrombosis, pulmonary
edema, CHF. GI:
Mild transient diarrhea. Hematologic:
Unmasking of polycythemia vera (with correction of vitamin B12
Itching, rash, flushing. Special Senses:
Severe optic nerve atrophy (patients with Leber's disease).
Diagnostic Test Interference
Most antibiotics, methotrexate, and pyrimethamine may produce invalid diagnostic blood assays for vitamin B12. Possibility of false-positive test for intrinsic factor antibodies.
Interactions Drug: Alcohol, aminosalicylic acid, neomycin, colchicine
may decrease absorption of oral cyanocobalamin; chloramphenicol
may interfere with therapeutic response to cyanocobalamin.
Intestinal absorption requires presence of intrinsic factor in terminal ileum. Distribution:
Widely distributed; principally stored in liver, kidneys, and adrenals; crosses placenta, excreted in breast milk. Metabolism:
Converted in tissues to active co-enzymes; enterohepatically cycled. Elimination:
5095% of doses ≥100 mcg are excreted in urine in 48 h. Half-Life:
6 d (400 d in liver).
Assessment & Drug Effects
- Lab tests: Before initiation of therapy, reticulocyte and erythrocyte counts, Hgb, Hct, vitamin B12, and serum folate levels should be determined; then repeated between 5 and 7 d after start of therapy and at regular intervals
during therapy. Monitor potassium levels during the first 48 h. Conversion to normal erythropoiesis increases erythrocyte
potassium requirement and can result in severe hypokalemia and sudden death.
- Obtain a careful history of sensitivities. Sensitization to cyanocobalamin can take as long as 8 y to develop.
- Monitor vital signs in patients with cardiac disease and in those receiving parenteral cyanocobalamin, and be alert to symptoms
of pulmonary edema, which generally occur early in therapy.
- Therapeutic response to drug therapy is usually dramatic, occurring within 48 h. Effectiveness is measured by laboratory
values and improvement in manifestations of vitamin B12 deficiency.
- Characteristically, reticulocyte concentration rises in 34 d, peaks in 58 d, and then gradually declines as
erythrocyte count and Hgb rise to normal levels (in 46 wk).
- Obtain a complete diet and drug history and inquire into alcohol drinking patterns for all patients receiving cyanocobalamin
to identify and correct poor habits.
Patient & Family Education
- Notify physician of any intercurrent disease or infection. Increased dosage may be required.
- To prevent irreversible neurologic damage resulting from pernicious anemia, drug therapy must be continued throughout life.
- Rich food sources of B12 are nutrient-added breakfast cereals, vitamin B12-fortified soy milk, organ meats, clams, oysters, egg yolk, crab, salmon, sardines, muscle meat, milk, and dairy products.