Drug information of cyanocobalamin


Drug group:

Nascobal (for use in the nose) is used to treat vitamin B12 deficiency in people with pernicious anemia and other conditions.
Nascobal is usually given after treatment with an injection form of Nascobal.

Mechanism of effect

Vitamin B12 can be converted to coenzyme B12 in tissues, and as such is essential for conversion of methylmalonate to succinate and synthesis of methionine from homocysteine, a reaction which also requires folate. In the absence of coenzyme B12, tetrahydrofolate cannot be regenerated from its inactive storage form, 5-methyltetrahydrofolate, and a functional folate deficiency occurs. Vitamin B12 also may be involved in maintaining sulfhydryl (SH) groups in the reduced form required by many SH-activated enzyme systems. Through these reactions, vitamin B12 is associated with fat and carbohydrate metabolism and protein synthesis.


Parenteral (intramuscular) administration of vitamin B12 completely reverses the megaloblastic anemia and GI symptoms of vitamin B12 deficiency; the degree of improvement in neurologic symptoms depends on the duration and severity of the lesions, although progression of the lesions is immediately arrested. In pernicious anemia patients, once weekly intranasal dosing with 500 mcg B12 gel resulted in a consistent increase in pre-dose serum B12 levels during one month of treatment (p < 0.003) above that seen one month after 100 mcg intramuscular dose .


Vitamin B12 is bound to intrinsic factor during transit through the stomach; separation occurs in the terminal ileum in the presence of calcium, and vitamin B12 enters the mucosal cell for absorption. It is then transported by the transcobalamin binding proteins. A small amount (approximately 1% of the total amount ingested) is absorbed by simple diffusion, but this mechanism is adequate only with very large doses.
A three way crossover study in 25 fasting healthy subjects was conducted to compare the bioavailability of the B12 nasal spray to the B12 nasal gel and to evaluate the relative bioavailability of the nasal formulations as compared to the intramuscular injection. The peak concentrations after administration of intranasal spray were reached in 1.25 +/- 1.9 hours. The mean peak plasma concentration (Cmax) of B12, obtained after baseline correction, following administration of intranasal spray were 748 +/-549 pg/mL. The bioavailability of the B12 nasal spray was found to be 10% less than the B12 nasal gel.
In the blood, B12 is bound to transcobalamin II, a specific B-globulin carrier protein, and is distributed and stored primarily in the liver and bone marrow.
About 3-8 mcg of B12 is secreted into the GI tract daily via the bile and undergoes some enterohepatic recycling; in normal subjects with sufficient intrinsic factor, all but about 1 mcg is reabsorbed. When B12 is administered in doses which saturate the binding capacity of plasma proteins and the liver, the unbound B12 is rapidly eliminated in the urine. Retention of B12 in the body is dose-dependent. About 80-90% of an intramuscular dose up to 50 mcg is retained in the body; this percentage drops to 55% for a 100 mcg dose, and decreases to 15% when a 1000 mcg dose is given.

Drug indications

Nascobal is indicated for:
Vitamin B12 maintenance therapy in adult patients with pernicious anemia who are in remission following intramuscular vitamin B12 therapy and who have no nervous system involvement
Treatment of adult patients with dietary, drug-induced, or malabsorption-related vitamin B12 deficiency not due to pernicious anemia
Prevention of vitamin B12 deficiency in adult patients with vitamin B12 requirements in excess of normal


The recommended initial dose of NASCOBAL is one spray (500 mcg) administered in ONE nostril once weekly. Administer NASCOBAL at least one hour before or one hour after ingestion of hot foods or liquids since hot foods may cause nasal secretions and a resulting loss of medication. Defer use of NASCOBAL in patients with nasal congestion, allergic rhinitis, or upper respiratory infections until after symptoms have subsided.

Drug contraindications

Nascobal is contraindicated in patients with hypersensitivity to cobalt and/or vitamin B12 or any of its excipients. Anaphylactic shock and death have been reported after parenteral vitamin B12 administration in sensitive patients.
parenteral indication

Side effects

Check with your doctor or nurse immediately if any of the following side effects occur while taking cyanocobalamin:
Abdominal or stomach pain
bleeding from the gums or nose
blue lips and fingernails
chest pain
coughing that sometimes produces a pink frothy sputum
decreased urine output
difficult, fast, noisy breathing, sometimes with wheezing
difficulty with swallowing
dilated neck veins
extreme fatigue
eye pain
fast heartbeat
hives, itching, or skin rash
increased sweating
irregular breathing
irregular heartbeat
pale skin
puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
ringing in the ears
swelling of the face, fingers, feet, or lower legs
tightness in the chest
unusual tiredness or weakness
weight gain


Chloramphenicol may decrease the efficacy of Nascobal when used for treatment of anemia. If Nascobal is used for the treatment of anemia concomitantly with chloramphenicol, monitor for reduced efficacy and if needed, consider an alternative therapy


Severe Optic Atrophy in Patients with Leber’s Disease
Patients with early Leber’s disease (hereditary optic nerve atrophy) who were treated with vitamin B12 suffered severe and swift optic atrophy. Cyanocobalamin products, including Nascobal, is not recommended for use in patients with Leber’s optic atrophy. For patients with Leber’s disease requiring vitamin B12, consider alternative therapy (e.g., hydroxocobalamin) for B12 supplementation.
Anaphylactic Reactions
Anaphylactic shock and death have been reported after parenteral vitamin B12 administration. If patients are to start Nascobal before having tolerated cyanocobalamin parenterally, consider administering an intradermal test dose of parenteral vitamin B12 to patients suspected of cyanocobalamin hypersensitivity [see Dosage and Administration (2.1)].
Masking of Folate Deficiency with Vitamin B12 Use
Doses of vitamin B12 exceeding 10 mcg daily may produce hematologic response in patients with folate deficient megaloblastic anemia and may therefore mask a previously unrecognized folate deficiency. Vitamin B12 is not a substitute for folic acid [see Dosage and Administration (2.4)]. Assess both vitamin B12 and folate levels prior to initiating therapy with vitamin B12, including Nascobal, or with folic acid [see Dosage and Administration (2.1)].
Hypokalemia and Thrombocytosis Due to Intense Treatment of Megaloblastic Anemia
Hypokalemia and sudden death may occur in severe megaloblastic anemia that is treated intensely with vitamin B12. Hypokalemia and thrombocytosis can occur upon conversion of severe megaloblastic anemia to normal erythropoiesis with vitamin B12 therapy. Therefore, serum potassium levels and platelet count should be monitored carefully during therapy [see Dosage and Administration (2.3)].
Unmasking of Polycythemia Vera
Vitamin B12 deficiency may suppress the signs of polycythemia vera. Treatment with vitamin B12 may unmask this condition. Patients exhibiting clinical or hematologic response consistent with polycythemia vera should be referred for further evaluation.

Points of recommendation

Nascobal should be administered with other therapy(ies) in:
Patients with concurrent folate and vitamin B12 deficiency:Administer folic acid in addition to Nascobal
Patients with concurrent iron and vitamin B12 deficiency:Administer iron in addition to Nascobal
Patients with correctible causes of vitamin B12 deficiency:Consider measures to treat the underlying condition associated with vitamin B12 deficiency in addition to treatment with Nascobal

Pregnancy level

The limited available data on Nascobal in pregnant women are insufficient to inform a drug-associated risk of adverse developmental outcomes. However, vitamin B12 is an essential vitamin and requirements are increased during pregnancy.
Animal reproduction studies have not been conducted with vitamin B12.

Breast feeding warning

Vitamin B12 is present in the milk of lactating women in concentrations which approximate the mother’s vitamin B12 blood level. Vitamin B12 does not appear to pose more than a minimal risk to breastfeeding children.

Related drugs

vitamine B12

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