vitamin B12

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(′vīd·ə·mən ¦bē¦twelv)

(biochemistry) A group of closely related polypyrrole compounds containing trivalent cobalt; the antipernicious anemia factor, essential for normal hemopoiesis. Also known as cobalamin; cyanocobalamin; extrinsic factor.

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A group of closely related polypyrrole compounds, with the structure shown, containing trivalent cobalt; it is often called cobalamin, The vitamin is a dark-red crystalline compound; in aqueous solution and at room temperature it is most stable at pH 4–7.

Vitamin B₁₂ deficiency in animals is characterized primarily by anemia and neuropathy. In humans, this deficiency is called pernicious anemia. People suffering from this disease lack a factor secreted in gastric juice which, by affecting absorption directly and by protecting vitamin B₁₂ from intestinal destruction, enables the vitamin to be absorbed. See also Anemia.

Requirements for vitamin B₁₂ are increased by reproduction or hyperthyroidism. Of the known vitamins B₁₂ is the most active biologically. A daily injection of 1 microgram of vitamin B₁₂ will prevent the recurrence of symptoms in people with pernicious anemia. For normal people a diet containing 3–5 μg per day (providing 1–1.5 μg absorbed) will satisfy vitamin B₁₂ requirements. See also Vitamin.

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A cobalt-containing compound, cobalamin, essential for normal metabolism of folic acid, and hence for cell division. Deficiency leads to pernicious anaemia when immature red blood cell precursors are released into the bloodstream, and there is degeneration of the spinal cord. The absorption of vitamin B₁₂ requires a specific protein (intrinsic factor) which is secreted in the gastric juice and it is failure of absorption, rather than dietary deficiency, that is the more usual cause of the problem. However, B₁₂ is found only in animal foods so vegans have to rely on bacterial preparations.

Meat, eggs, and dairy produce are rich sources and dietary deficiency is unlikely except among vegans.

Brand names: Berdoz™Cobal 100™Cobal 1000™Cyano™Cyanoject™Cybolin-12™Cyomin®LA-12™Nascobal®Neuroforte R™Nutri-Twelve™Primabalt™ 1000Twelve Resin-KVita 12™

Chemical formula:

Drug Forms:
• Cyanocobalamin (Vitamin B12) Nasal gel (below)
• Cyanocobalamin, Vitamin B₁₂ tablets
• Cyanocobalamin, Vitamin B₁₂ capsules
• Cyanocobalamin, Vitamin B₁₂ nasal gel
• Cyanocobalamin, Vitamin B ₁₂ nasal spray
• Cyanocobalamin (Vitamin B12) Nasal spray, solution
• Cyanocobalamin (Vitamin B12) Oral tablet
• Cyanocobalamin (Vitamin B12) Oral tablet, extended-release
• Cyanocobalamin (Vitamin B12) Solution for injection

Español:
• Cianocobalamina (Vitamina B12), Gel nasal
• Tabletas de cianocobalamina, vitamina B₁₂
• Cápsulas de cianocobalamina, vitamina B₁₂
• Gel nasal de cianocobalamina, vitamina B₁₂
• Cianocobalamina (Vitamina B12) Aerosol nasal, solución
• Cianocobalamina (Vitamina B12), Tableta oral
• Cianocobalamina (Vitamina B12), Tableta oral de liberación prolongada
• Cianocobalamina (Vitamina B12), Solución para inyección

Cyanocobalamin (Vitamin B12) Nasal gel

What is this medicine?

CYANOCOBALAMIN is a man made form of vitamin B12. Vitamin B12 is used in the growth of healthy blood cells, nerve cells, and proteins in the body. It also helps with the metabolism of fats and carbohydrates. This medicine is used to treat people who can not absorb enough vitamin B12.

This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of these conditions:
•Leber's disease
•low amounts of iron or folic acid in your blood
•megaloblastic anemia
•nasal congestion from allergies or infection
•an unusual or allergic reaction to cyanocobalamin, cobalt, other medicines, foods, dyes, or preservatives
•pregnant or trying to get pregnant
•breast-feeding

How should I use this medicine?

This medicine is for use in the nose only. Follow the directions on the prescription label. You may not get the full dose of this medicine if you have a runny nose. Do not use this medicine for at least one hour before or after hot foods or liquids. Talk to your doctor if you get a runny nose from allergies or a cold. Do not use more often than directed. Make sure that you are using your nasal gel correctly. Ask you doctor or health care provider if you have any questions.

A patient information sheet for the product will be given with each prescription and refill. Read this sheet carefully each time. The sheet may change frequently.

Talk to your pediatrician regarding the use of this medicine in children. Special care may be needed.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.
NOTE: This medicine is only for you. Do not share this medicine with others.

What may interact with this medicine?

•alcohol
•aminosalicylic acid
•colchicine
•medicines that suppress your bone marrow like chemotherapy, chloramphenicol

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

What should I watch for while using this medicine?

Visit your doctor or health care professional regularly. You may need blood work done while you are taking this medicine.

You may need to follow a special diet. Talk to your doctor. Limit your alcohol intake and avoid smoking to get the best benefit from this medicine.

What side effects may I notice from receiving this medicine?

Side effects that you should report to your doctor or health care professional as soon as possible:
•allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue
•breathing problems
•chest tightness, pain
•dizziness
•fever, infection
•pain, swelling, warmth in the leg

Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):
•headache
•nausea
•runny nose

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Where should I keep my medicine?

Keep out of the reach of children.

Store the container upright at room temperature between 15 and 30 degrees C (59 and 85 degrees F). Protect from light. Keep in carton until ready to use. Do not freeze. Throw away any unused medicine after the expiration date.

Last updated: 3/3/2005 2:49:00 PM

Important Disclaimer: The drug information provided here is for educational purposes only. It is intended to supplement, not substitute for, the diagnosis, treatment and advice of a medical professional. This drug information does not cover all possible uses, precautions, side effects and interactions. It should not be construed to indicate that this or any drug is safe for you. Consult your medical professional for guidance before using any prescription or over the counter drugs.

Description

Cobalamin, also known as B₁₂, is a member of the water-soluble family of B vitamins. It is a key factor in the body's proper use of iron and formation of red blood cells. The nervous system also relies on an adequate supply of cobalamin to function appropriately, as it is an essential component in the creation and maintenance of the myelin sheath that lines nerve cells. Other roles of cobalamin include working with pyridoxine (vitamin B₆ and folic acid to reduce harmful homocysteine levels, participating in the metabolization of food, and keeping the immune system operating smoothly.

General Use

Very small amounts of cobalamin are needed to maintain good health. The RDA value is 0.3 micrograms (mcg) for infants under 6 months, 0.5 mcg for those 6 months to 1 year old, 0.7 mcg for children 1-3 years old, 1.0 mcg for children 4-6 years old, 1.4 mcg for children 7-10 years old, and 2 mcg for those 11 years of age and older. Requirements are slightly higher for pregnant (2.2 mcg) and lactating (2.6 mcg) women.

The primary conditions that benefit from supplementation with cobalamin are megaloblastic and pernicious anemia. Megaloblastic anemia is a state resulting from an inadequate intake of cobalamin, to which vegans are particularly susceptible because of the lack of animal food sources. Vegans, who do not consume any animal products including meat, dairy, or eggs, should take at least 2 mcg of cobalamin per day in order to prevent this condition. In the case of pernicious anemia, intake may be appropriate but absorption is poor due to a lack of normal stomach substance, called intrinsic factor, that facilitates absorption of vitamin B₁₂. Large doses are required to treat pernicious anemia, which occurs most commonly in the elderly population as a result of decreased production of intrinsic factor by the stomach. Supplements are generally effective when taken orally in very large amounts (300-1000 mcg/day) even if no intrinsic factor is produced. These supplements require a prescription, and should be administered with the guidance of a health care provider. Injections, instead of the supplements, are often used.

Those who have infections, burns, some types of cancer, recent surgery, illnesses that cause decay or loss of strength, or high amounts of stress may need more than the RDA amount of B₁₂ and other B vitamins. A balanced supplement is the best approach.

Male infertility can sometimes be resolved through use of cobalamin supplements. Other conditions that may be improved by cobalamin supplementation include: asthma, atherosclerosis (hardening of the arteries caused by plaque formation in the arteries), bursitis (inflammation of a bodily pouch, especially the shoulder or elbow), Crohn's disease (chronic recurrent inflammation of the intestines), depression, diabetes, high cholesterol, osteoporosis, and vitiligo (milky-white patches on the skin). There is not enough evidence to judge whether supplementation for these diseases is effective.

Preparations

Natural Sources

Usable cobalamin is only found naturally in animal source foods. Fresh food is best, as freezing and exposure to light may destroy some of the vitamin content. Clams and beef liver have very high cobalamin levels. Other good sources include chicken liver, beef, lamb, tuna, flounder, liverwurst, eggs, and dairy products. Some plant foods may contain cobalamin, but it is not in a form that is usable by the body.

Supplemental Sources

Cobalamin supplements are available in both oral and injectable formulations. A nasal gel is also made. Generally a balanced B-complex vitamin is preferable to taking high doses of cobalamin unless there is a specific indication for it, such as megaloblastic anemia. Strict vegetarians will need to incorporate a supplemental source of B₁₂ in the diet. Cyanocobalamin is the form most commonly available in supplements. Two other, possibly more effective, types are hydrocobalamin and methyl-cobalamin. As with all supplements, cobalamin should be stored in a cool, dry, dark place and out of the reach of children.

Deficiency

Cobalamin deficiency may be manifested as a variety of symptoms since cobalamin is so widely used in the body. Severe fatigue may occur initially. Effects on the nervous system can be wide-ranging, and include weakness, numbness and tingling of the limbs, memory loss, confusion, delusion, poor balance and reflexes, hearing difficulties, and even dementia. Severe deficiency may appear similar to multiple sclerosis. Nausea and diarrhea are possible gastrointestinal signs. The anemia that results from prolonged deficiency may also be seen as a pallor, especially in mucous membranes such as the gums and the lining of the inner surface of the eye.

Megaloblastic anemia is a common result of inadequate cobalamin. This condition can also result if a person stops secreting enough intrinsic factor in the stomach, a substance essential for the absorption of cobalamin. Inadequate intrinsic factor leads to pernicious anemia, so called because it persists despite iron supplementation. Long-term deficiencies of cobalamin also allow homocysteine levels to build up. Negative effects of large amounts of circulating homocysteine include heart disease, and possibly brain toxicity. Taking high levels of folic acid supplements can mask cobalamin deficiency and prevent the development of megaloblastic anemia, but neurological damage can still occur. This damage may become permanent if the cobalamin deficiency persists for a long period of time.

Risk Factors for Deficiency

The primary groups at risk for cobalamin deficiency are vegans who are not taking supplements, and the elderly. Older adults are more likely to have both insufficient intrinsic factor secreted by the stomach and low levels of stomach acid, causing cobalamin to be poorly absorbed. Malabsorptive diseases and stomach surgery can also predispose to a deficiency.

Precautions

People who are sensitive to cobalamin or cobalt should not take cobalamin supplements. Symptoms of hypersensitivity may include swelling, itching, and shock. Adverse effects resulting from B₁₂ supplementation are rare. Cobalamin should also be avoided by those who have a type of hereditary optic nerve atrophy known as Leber's disease.

Side Effects

Very high doses of cobalamin may sometimes cause acne.

Interactions

Large amounts of vitamin C taken within an hour of vitamin B supplements will destroy the cobalamin component. Absorption of cobalamin is also impaired by deficiencies of folic acid, iron, or vitamin E. Improved absorption occurs when it is taken with other B vitamins or calcium. Some medications may also cause an increased use or decreased absorption of this vitamin. Those on colchicine, corticosteroids, methotrexate, metformin, phenformin, oral contraceptives, cholestyramine, colestipol, clofibrate, epoetin, neomycin, or supplemental potassium may need extra cobalamin. Use of nicotine products or excessive alcohol can deplete B₁₂.

Resources

Books

Bratman, Steven, and David Kroll. Natural Health Bible. CA Prima Publishing, 1999.

Feinstein, Alice. Prevention's Healing with Vitamins. PA: Rodale Press, 1996.

Griffith, H. Winter. Vitamins, Herbs, Minerals & Supplements: The Complete Guide. AZ: Fisher Books, 1998.

Jellin, Jeff, Forrest Batz, and Kathy Hitchens. Pharmacist's Letter/Prescriber's Letter Natural Medicines Comprehensive Database. CA: Therapeutic Research Faculty, 1999.

Pressman, Alan H. and Sheila Buff. The Complete Idiot's Guide to Vitamins and Minerals. New York: Alpha Books, 1997.

[Article by: Judith Turner]

A factor external to the human body, such as equipment and playing surfaces.

IN BRIEF: n. - A B vitamin that is used to treat pernicious anemia.

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