Uses
Vitamin B12 Deficiency
Treatment of pernicious anemia and other vitamin B12 deficiency states.
Parenteral cyanocobalamin or hydroxocobalamin: Treatment of vitamin B12 deficiency due to inadequate intrinsic factor (IF) secretion; impaired intestinal absorption; or dietary deficiency associated with a vegetarian diet.
Cyanocobalamin is considered the parenteral vitamin B12 preparation of choice; hydroxocobalamin may be preferred for initial treatment.
Cyanocobalamin nasal spray: Used to maintain hematologic status in adults with pernicious anemia with no nervous system involvement who have responded to parenteral vitamin B 12 therapy. Also used as a supplement for vitamin B12 deficiency due to dietary deficiency, impaired absorption, inadequate secretion of IF, or certain other conditions.
Dietary Requirements
Adequate intake needed to prevent vitamin B12 deficiency and neurologic complications associated with vitamin B12 deficiency.
Adequate intake of vitamin B12 usually can be accomplished through consumption of foodstuffs; however, about 10–30% of geriatric individuals are unable to absorb naturally occurring vitamin B12 and should consume vitamin B12-fortified food or supplements. Inadequate intake can occur in vegetarians and their breast-fed infants. Mixed foods whose main ingredient is meat, fish, or poultry; milk; and fortified ready-to-eat cereals are the main sources of vitamin B12 in the diet of US adults and children.
Recommended Dietary Allowance (RDA) in adults based on amount needed to maintain hematologic status and normal serum vitamin B12 concentrations.
Adequate intake (AI) established for infants ≤6 months of age based on observed mean vitamin B12 intake of infants fed principally human milk; AI for infants 7–12 months of age based on AI for younger infants and data in adults.
RDA for children 1–18 years of age based on data in adults.
Metabolic Disorders
Parenteral cyanocobalamin: Management of hereditary deficiency of transcobalamin II.
Schilling Test
Parenteral cyanocobalamin and hydroxocobalamin: Used in conjunction with cyanocobalamin Co 57 in Schilling test to study vitamin B12 absorption.
Cyanide Poisoning
Hydroxocobalamin (Cyanokit®): Treatment of known or suspected cyanide poisoning. Used in conjunction with airway and cardiovascular support and management of seizure activity.
Dosage and Administration
Administration
Cyanocobalamin is administered orally, intranasally, or by IM or deep sub-Q injection.
Hydroxocobalamin is administered by IM injection or IV infusion.
Oral Administration
Oral therapy is inferior to parenteral therapy. May be used for treatment of dietary vitamin B12 deficiency in patients with normal GI absorption.
Parenteral Administration
Cyanocobalamin: Administer by IM or deep sub-Q injection. If administered sub-Q, avoid injection into the dermis or upper subcutaneous tissue. Avoid administering IV; vitamin is rapidly excreted in urine when administered IV.
Hydroxocobalamin: Administer by IM injection (vitamin deficiency) or by IV infusion (cyanide poisoning). Avoid administering IV for vitamin deficiency.
For drug compatibility information, see Compatibility under Stability.
IV Administration for Cyanide Poisoning
Hydroxocobalamin: (Cyanokit®); Administer by IV infusion.
May require a dedicated IV line. Administration through the same IV line as blood products not recommended.
Reconstitution
Reconstitute vial containing 2.5 g of hydroxocobalamin with 100 mL of 0.9% sodium chloride injection; invert or rock vial for at least 30 seconds. Do not shake vial. Lactated Ringer's injection or 5% dextrose injection can be used if 0.9% sodium chloride injection is not available. Reconstituted solution contains 25 mg/mL.
Rate of Administration
Initial 5-g dose: 15 minutes.
Second 5-g dose: 15 minutes (for patients in extremis) to 2 hours; rate depends on patient condition.
Intranasal Administration
Administer intranasally using a metered-dose pump. Administer 1 hour before or 1 hour after ingestion of hot foods or liquids.
Prior to intranasal administration, clear nasal passages. Insert the nasal adapter 1 cm into one nostril, point the tip of the adapter toward the back of the nose, hold the other nostril closed, and tilt head slightly forward, pump the drug into nostril, sniff gently during and immediately after dosing, return head to upright position, remove pump unit from nose.
Efficacy has not been established in patients with nasal congestion, allergic rhinitis, or upper respiratory tract infection; defer use until these symptoms have subsided.
Prime the pump before each use.
Dosage
Vitamin B 12 deficiency: Duration of therapy depends on cause; long-term therapy not needed when other therapeutic measures correct the underlying cause of the deficiency.
Cyanocobalamin metered-dose pump delivers 500 mcg of the drug (0.1 mL) per actuation.
Pediatric Patients
Vitamin B 12 Deficiency
IM
Hydroxocobalamin: Initially, single doses of 100 mcg to total dose of 1–5 mg given over ≥2 weeks.
Hydroxocobalamin: Maintenance, 30–50 mcg every 4 weeks.
Dietary and Replacement Requirements
Oral
Infants born to vegan mothers: Supplement with AI from birth because these infants' vitamin B12 stores are low and their mother’s milk may supply very small amounts of the vitamin.
Infants ≤6 months of age: Recommended AI is 0.4 mcg (0.06 mcg/kg) daily.
Infants 7–12 months of age: Recommended AI is 0.5 mcg (0.06 mcg/kg) daily.
Children 1–3 years of age: RDA is 0.9 mcg daily.
Children 4–8 years of age: RDA is 1.2 mcg daily.
Children 9–13 years of age: RDA is 1.8 mcg daily.
Children 14-18 years of age: RDA is 2.4 mcg daily.
The RDAs will not meet the needs of individuals with malabsorption syndrome.
Cyanide Poisoning
IV
Hydroxocobalamin: 70 mg/kg has been used.†
Adults
Vitamin B 12 Deficiency
IM or Sub-Q
Cyanocobalamin: Initially, 100 mcg daily for 6–7 days. If clinical manifestations improve and reticulocyte response observed, administer 100 mcg every other day for 7 doses and then 100 mcg every 3–4 days for 2–3 weeks.
Cyanocobalamin: Maintenance, 100 mcg every month.
IM
Hydroxocobalamin: Initially, 30 mcg daily for 5–10 days.
Hydroxocobalamin: Maintenance, 100–200 mcg every month.
Intranasal
Maintenance, 500 mcg (one actuation) once weekly. Increase dose in patients who experience a decline in serum vitamin B12 concentrations after 1 month of therapy.
Dietary and Replacement Requirements
Oral
Men and women ≥19 years of age: RDA is 2.4 mcg daily.
Adults ≥51 years of age should obtain most of their vitamin B12 from fortified food or a vitamin B12 supplement.
The RDAs will not meet the needs of individuals with malabsorption syndrome.
Cyanide Poisoning
IV
Hydroxocobalamin: Initially, 5 g (two 2.5-g vials). A second 5-g dose may be administered, based on the severity of the poisoning and clinical response.
Schilling Test
IM or Sub-Q
Cyanocobalamin: Flushing dose is 1000 mcg.
IM
Hydroxocobalamin: Flushing dose is 1000 mcg.
Special Populations
Pregnant Women
RDA for pregnant women is 2.6 mcg daily.
Lactating Women
RDA for lactating women is 2.8 mcg daily.
Requirements increased in lactating women to ensure adequate concentration of the vitamin in milk.
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