Prescription Vitamin B12 Names
The prescription names for vitamin B12 are hydroxocobalamin and cyanocobalamin, with hydroxocobalamin being the preferred formulation recommended by major medical guidelines. 1, 2
Available Prescription Formulations
Hydroxocobalamin (Preferred)
- Hydroxocobalamin is the guideline-recommended formulation across all major medical societies, including the British Medical Journal guidelines, due to its established dosing protocols and superior tissue retention. 1
- Available as intramuscular injection at 1000 mcg (1 mg) per mL concentration. 2
- The FDA-approved formulation contains hydroxocobalamin acetate equivalent to 1000 mcg hydroxocobalamin per mL. 2
Cyanocobalamin
- Cyanocobalamin is the most widely used form of vitamin B12 and has hematopoietic activity apparently identical to that of the antianemia factor in purified liver extract. 3
- Available in both oral and intramuscular formulations. 3
- Should be avoided in patients with renal dysfunction due to potential accumulation of cyanide and increased cardiovascular risk (hazard ratio 2.0 for composite cardiovascular outcomes). 1
Methylcobalamin
- Methylcobalamin is one of the two active co-enzyme forms of vitamin B12, primarily involved in hematopoiesis and brain development. 4
- May be preferable to cyanocobalamin in patients with renal dysfunction. 5
- Less commonly prescribed than hydroxocobalamin, with fewer established dosing protocols in guidelines. 1
Clinical Selection Algorithm
When choosing a prescription B12 formulation:
First-line choice: Hydroxocobalamin for all patients requiring intramuscular therapy, as it has the most robust evidence base and guideline support. 1, 2
Avoid cyanocobalamin if: Patient has renal dysfunction, diabetic nephropathy, or chronic kidney disease—use hydroxocobalamin or methylcobalamin instead. 1, 5
Consider methylcobalamin if: Patient has renal impairment and requires an alternative to hydroxocobalamin. 5
Standard Prescription Dosing
For deficiency without neurological symptoms: Hydroxocobalamin 1 mg intramuscularly three times a week for 2 weeks, then 1 mg every 2-3 months for life. 1, 5
For deficiency with neurological involvement: Hydroxocobalamin 1 mg intramuscularly on alternate days until no further improvement, then 1 mg every 2 months for life. 1, 5
For maintenance therapy: Hydroxocobalamin 1000 mcg intramuscularly every 2-3 months, though some patients may require monthly dosing to meet metabolic requirements. 1, 5
Important Prescribing Considerations
- The cobalt content of hydroxocobalamin is 4.34%, and it appears as dark red orthorhombic needles or crystalline red powder. 2
- Vitamin B12 coenzymes are very unstable in light, requiring proper storage. 2
- Never prescribe folic acid before ensuring adequate B12 treatment, as folic acid can mask B12 deficiency anemia while allowing irreversible neurological damage to progress. 1, 5