cyanocobalamin (vitamin B12, Nascobal, Athlete, Calomist, cobalamin, Cobex, Crystamine, Prime, Rubramin PC, Vibisone, Eligen B12)

Dosing and uses of Vitamin B12, Athlete (cyanocobalamin)

• Adult
• Pediatric

 

Adult dosage forms and strengths

tablet

• 100mcg
• 250mcg
• 500mcg
• 1000mcg

tablet, extended release

• 1000mcg

tablet, sublinguaL

• 2500mcg

injectable solution

• 1000mcg/mL

nasal spray

• 500mcg/spray

 

Nutritional Supplementation

Recommended daily allowance (RDA)

>19 years: 2.4 mcg

Pregnant women: 2.6 mcg

Breastfeeding women: 2.8 mcg

Dietary supplement: 50-6,000 mcg/day

 

Pernicious Anemia

Manufacturer recommendation: 100 mcg IM/SC once daily for 6-7 days, then every other day for 7 doses, then every 3-4 days for 2-3 weeks, then monthly

Alternative parenteral dosing: 1000 mcg IM/SC once daily for 7 days, then weekly for 1 month, then monthly

Nasal spray: 500 mcg (1 spray in 1 nostril) weekly; if patient is taking hot meals, spray should be administered 1 hour before or after meaL

 

B12 Deficiency

Initial: 30 mcg IM once daily for 5-10 days

Maintenance: 100-200 mcg IM monthly

Nasal dose: 500 mcg once weekly

Dosing considerations

• PO absorption requires intrinsic factor
• Cyanide poisoning: See Hydroxycobalamin AD

 

Pediatric dosage forms and strengths

tablet

• 100mcg
• 250mcg
• 500mcg
• 1000mcg

tablet, extended release

• 1000mcg

tablet, sublinguaL

• 2500mcg

injectable solution

• 1000mcg/mL

nasal spray

• 500mcg/spray

 

Nutritional Supplementation

RDA

0-6 months: 0.4 mcg

7-12 months: 0.5 mcg

1-3 years: 0.9 mcg

4-8 years: 1.2 mcg

9-13 years: 1.8 mcg

>14 years: 2.4 mcg

 

Pernicious Anemia

30-50 mcg IM/SC once daily for &ge2 weeks for total dose of 1,000 mcg to 5,000 mcg administer concomitantly with 1 mg/day of folic acid for 1 month

Maintenance: 100 mcg IM/SC monthly

 

B12 Deficiency

0.2 mcg/kg for 2 days; follow by 1,000 mcg/day for 2-7 days; follow by 100 mcg/day for 2-7 days; then 100 mcg/week for 1 month

Maintenance: 100 mcg IM/SC monthly

 

Vitamin B12, Athlete (cyanocobalamin) adverse (side) effects

>10%

Arthralgia (12%)

Dizziness (12%)

Headache (12%)

Nasopharyngitis (12%)

 

Frequency not defined

Anaphylaxis

Angioedema

Congestive heart failure

Peripheral vascular disease

Pulmonary edema

Diarrhea

Dyspepsia

Polycythemia vera

Sore throat

Nervousness

Rhinitis

Glossitis

Hypoesthesia

 

Warnings

Contraindications

Hypersensitivity to product; sensitivity to cobalt

 

Cautions

Intensive treatment of B12-deficient megaloblastic anemia may cause hypokalemia and sudden death

Nasal disease; defer use until symptoms resolve

Use with caution in patients with Leber optic nerve atrophy

Injection is incompatible with some common drugs (eg, warfarin and several phenothiazines) but is compatible with vitamins B and C

Vitamin B12 deficiency for >3 months results in irreversible degenerative CNS lesions

Thrombocytosis may occur with treatment of severe vitamin B12 megaloblastic anemia

Oral and intranasal route are not indicated for the treatment of pernicious anemia until symptoms resolve

 

Pregnancy and lactation

Pregnancy category: A; C (for doses exceeding RDA and for intranasal products)

Lactation: Drug distributed in milk; safe to use

 

Pregnancy categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

 

Pharmacology of Vitamin B12, Athlete (cyanocobalamin)

Mechanism of action

Coenzyme; metabolic functions include protein synthesis and carbohydrate metabolism

Plays role in cell replication and hematopoiesis

 

Absorption

Bioavailability: 6.1% (intranasal solution relative to IM)

 

Distribution

Distributed to liver, bone marrow, and other tissues

Protein bound: Binding to transcobalamins

 

Elimination

Excretion: Urine (excess amount), bile (mostly reabsorbed)