cyanocobalamin

REMS

Vitamin B₁₂ deficiency (parenteral products or nasal spray should be used when deficiency is due to malabsorption).
Pernicious anemia (parenteral products should be used for initial therapy; nasal or oral products are not indicated until patients have achieved hematologic remission following parenteral therapy and have no signs of CNS involvement).
Part of the Schilling test (vitamin B₁₂ absorption test) (diagnostic).

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity;
Pedi: Avoid using preparations containing benzyl alcohol in premature infants (associated with fatal gasping syndrome).

Use Cautiously in:

Hereditary optic nerve atrophy (accelerates nerve damage);
Renal impairment (when using aluminum-containing products);
Uremia, folic acid deficiency, concurrent infection, iron deficiency (response to vitamin B₁₂ will be impaired).

Adv. Reactions/Side Effects ⬆ ⬇

CV: HF

Derm: itching, swelling of the body

F and E: hypokalemia

GI: diarrhea

Hemat: thrombocytosis

Local: pain at IM site

Neuro: headache

Resp: pulmonary edema

Misc: HYPERSENSITIVITY REACTIONS (INCLUDING ANAPHYLAXIS)

Interactions ⬆ ⬇

Drug-drug:

Chloramphenicol and antineoplastics may ↓ hematologic response.
Colchicine, aminosalicylic acid, or excessive intake of alcohol or vitamin C may ↓ absorption/effectiveness.

Availability ⬆ ⬇

(Generic available)

Tablets: 100 mcg^OTC; 250 mcg^OTC; 500 mcg^OTC; 1000 mcg^OTC
Extended-release tablets: 1000 mcg^OTC
Sublingual tablets: 2500 mcg ^OTC
Lozenges: 50 mcg^OTC; 100 mcg^OTC; 250 mcg^OTC; 500 mcg^OTC
Nasal spray: 500 mcg/0.1 mL actuation (8 sprays/bottle)
Solution for injection: 1000 mcg/mL

Route/Dosage ⬆ ⬇

Oral products are usually not recommended due to poor absorption and should be used only if patient refuses the intramuscular, deep SUBQ, or intranasal route of administration.

Vitamin B12 Deficiency

PO (Adults and Children ): Amount depends on deficiency (up to 1000 mcg/day have been used).
IM SC (Adults ): 30 mcg/day for 5–10 days; then 100–200 mcg/mo.
IM SC (Children ): 0.2 mcg/kg for 2 days; then 1000 mcg/day for 2–7 days; then 100 mcg/wk for 1 mo.
(Adults ): 500 mcg (one spray) in one nostril once weekly.

Pernicious Anemia

IM SC (Adults ): 100 mcg/day for 6–7 days; if improvement, give same dose every other day for 7 doses; then every 3–4 days for 2–3 wk; once hematologic values return to normal (remission), can give maintenance dose of 100 mcg/mo (doses up to 1000 mcg have been used for maintenance) (could alternatively use oral or intranasal formulations below for maintenance at specified doses).
PO (Adults ): For hematologic remission only: 1000–2000 mcg/day.
(Adults ): For hematologic remission only: 500 mcg (one spray) in one nostril once weekly.
IM SC (Children ): 30–50 mcg/day for 2 or more wk (to a total dose of 1000–5000 mcg); then give maintenance dose of 100 mcg/mo (doses up to 1000 mcg have been used for maintenance).

Schilling Test

IM SC (Adults ): Flushing dose is 1000 mcg.

US Brand Names ⬆ ⬇

Action ⬆ ⬇

Necessary coenzyme for metabolic processes, including fat and carbohydrate metabolism and protein synthesis.
Required for cell reproduction and hematopoiesis.

Therapeutic effects:

Corrects manifestations of pernicious anemia (megaloblastic indices, GI lesions, neurologic damage).
Corrects vitamin B₁₂ deficiency.
Schilling test confirms impaired vitamin B₁₂ absorption.

Classifications ⬆ ⬇

Therapeutic Classification: antianemics, vitamins

Pharmacologic Classification: water soluble vitamins

Pharmacokinetics ⬆ ⬇

Absorption: Oral absorption in GI tract requires intrinsic factor and calcium; well absorbed after IM, SUBQ, and nasal administration.

Distribution: Stored in the liver and bone marrow.

Metabolism/Excretion: Primarily excreted unchanged in urine.

Half-Life: 6 days (400 days in liver).

Time/Action Profile ⬆ ⬇

(reticulocytosis)

ROUTE	ONSET	PEAK	DURATION
IM	unknown	3–10 days	unknown
SUBQ	unknown	3–10 days	unknown
Nasal	unknown	3–10 days	unknown

Patient/Family Teaching ⬆ ⬇

Teach patient reason for vitamin B₁₂ therapy and side effects. Explain that they should take oral forms with food for best absorption and avoid alcohol during therapy. Advise patient to read Medication Guide before starting and periodically during therapy in case of changes.
Encourage patient to comply with diet recommendations of health care professional. Explain that the best source of vitamins is a well-balanced diet. Foods high in vitamin B₁₂ include meats, seafood, egg yolk, and fermented cheeses.
Patients self-medicating with vitamin supplements should be cautioned not to exceed RDA. Effectiveness of megadoses for treatment of various medical conditions is unproven and may cause side effects.
Inform patients with pernicious anemia of the lifelong need for vitamin B₁₂ replacement.
Emphasize the importance of follow-up exams to evaluate progress.
Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications. Counsel patient to avoid alcohol while taking this drug.
Rep: Advise patient to notify health care professional if pregnancy is planned or suspected or if breastfeeding.

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Indications ⬇