Usage
Cyanocobalamin is a man-made form of vitamin B12 used to treat and prevent vitamin B12 deficiency. Vitamin B12 is essential for proper functioning of the nervous system, red blood cell formation, and DNA synthesis. Deficiency can lead to various health problems, including megaloblastic anemia, nerve damage, and gastrointestinal issues.
It’s prescribed for conditions like:
- Pernicious anemia (an autoimmune disorder affecting B12 absorption)
- Dietary B12 deficiency (common in vegans and vegetarians)
- Malabsorption syndromes (e.g., Crohn’s disease, celiac disease)
- Other conditions leading to low B12 levels.
Pharmacological Classification: Vitamin supplement (water-soluble) and Hematopoietic agent.
Mechanism of Action: Cyanocobalamin is converted in the body to its active coenzyme forms, methylcobalamin and adenosylcobalamin. Methylcobalamin is crucial for the synthesis of methionine from homocysteine, which is important for DNA and RNA synthesis. Adenosylcobalamin is essential for the metabolism of fatty acids and carbohydrates.
Alternate Names
Brand Names: Nascobal, Athlete, Calomist, Cobex, Crystamine, Prime, Rubramine PC, Vibisone, Eligen B12, and others. (Note: Brand names can vary by region.)
How It Works
Pharmacodynamics: Cyanocobalamin, after conversion to its active forms, plays a vital role in:
- Hematopoiesis: Promotes normal red blood cell formation, preventing megaloblastic anemia.
- Neurological Function: Maintains the myelin sheath around nerves, preventing nerve damage.
- DNA Synthesis: Supports cell growth and replication.
Pharmacokinetics:
- Absorption: Absorption of oral cyanocobalamin requires intrinsic factor, a protein secreted by the stomach. Injections bypass this process and provide direct absorption. Nasal sprays offer direct absorption through the nasal mucosa.
- Distribution: Distributed widely throughout the body, primarily in the liver.
- Metabolism: Converted to active coenzyme forms, methylcobalamin and adenosylcobalamin.
- Elimination: Primarily excreted in urine. Excess amounts are also excreted in bile.
Mode of Action: The coenzyme forms of B12 are involved in enzymatic reactions:
- Methylcobalamin is a cofactor for methionine synthase, facilitating the conversion of homocysteine to methionine.
- Adenosylcobalamin is a cofactor for methylmalonyl-CoA mutase, converting methylmalonyl-CoA to succinyl-CoA.
Receptor Binding/Enzyme Inhibition/Neurotransmitter Modulation: Cyanocobalamin functions primarily as a coenzyme in enzymatic reactions, not through receptor binding or neurotransmitter modulation. It does not directly inhibit enzymes, but rather acts as a cofactor.
Elimination Pathways: Primarily renal excretion through glomerular filtration. Hepatic excretion through bile also plays a role.
Dosage
Standard Dosage
Adults:
- Dietary Deficiency: Oral: 50-150 mcg daily. Dosage can be adjusted based on individual needs.
- Pernicious Anemia/Severe Deficiency: Intramuscular (IM) or deep Subcutaneous (SC): Initially, 1000 mcg daily for 6-7 days, followed by 1000 mcg weekly for a month, and then 1000 mcg monthly as maintenance. Alternatively, 100 mcg IM/SC daily for 6-7 days, then every other day for 7 doses, then every 3-4 days for 2-3 weeks, and then monthly. Nasal spray: 500 mcg once weekly.
Children:
- Pernicious Anemia: IM or SC: 30-50 mcg daily for 2 weeks or more to reach a total dose of 1000-5000 mcg, administered with 1 mg/day folic acid for 1 month. Maintenance: 100 mcg monthly IM or SC.
- B12 Deficiency: Dosage is based on age and severity of deficiency. Consult pediatric dosing guidelines for specific recommendations.
Special Cases:
- Elderly Patients: Increased risk of B12 deficiency due to reduced absorption. Close monitoring and dose adjustment may be needed.
- Patients with Renal Impairment: Caution should be exercised due to potential aluminum toxicity in some formulations. Monitor renal function and adjust dose accordingly.
- Patients with Hepatic Dysfunction: Generally, no dose adjustment is necessary.
- Patients with Comorbid Conditions: Individualized dosing based on specific conditions.
Clinical Use Cases
The listed clinical use cases (Intubation, Surgical Procedures, Mechanical Ventilation, ICU Use, Emergency Situations) are not standard indications for Cyanocobalamin use. Its primary use is for vitamin B12 deficiency.
Dosage Adjustments
Dosage adjustments are necessary based on individual patient factors, such as severity of deficiency, response to treatment, and presence of renal impairment. Regular monitoring of B12 levels and complete blood count is essential.
Side Effects
Common Side Effects:
- Diarrhea
- Itching
- Swelling (edema)
Rare but Serious Side Effects:
- Allergic reactions (rash, hives, difficulty breathing, swelling)
- Heart failure
- Pulmonary edema
- Hypokalemia (low potassium)
Long-Term Effects:
- Polycythemia vera (increased red blood cell production) may be unmasked in predisposed individuals.
Adverse Drug Reactions (ADR):
- Anaphylaxis (rare but serious)
- Hypokalemia
- Congestive heart failure
- Pulmonary edema
Contraindications
- Hypersensitivity to cyanocobalamin or cobalt
- Leber’s hereditary optic neuropathy (can worsen the condition)
Drug Interactions
Cyanocobalamin may interact with various medications:
- Antibiotics: Some antibiotics can interfere with B12 absorption.
- Metformin: Long-term use of metformin can reduce B12 absorption.
- Proton Pump Inhibitors (PPIs): Reduced stomach acid can decrease B12 absorption.
- Other: Certain medications used for gout, cholesterol, and high blood pressure can also interact with cyanocobalamin.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: A (generally considered safe)
- Fetal Risks: No known adverse effects on the fetus. Adequate B12 intake during pregnancy is essential for fetal development.
- Breastfeeding: B12 passes into breast milk, but it’s generally safe. Maternal B12 supplementation is sometimes necessary to prevent neonatal deficiency, especially in vegetarian or vegan mothers.
Drug Profile Summary
- Mechanism of Action: Converted to active coenzyme forms involved in DNA synthesis, red blood cell formation, and nerve function.
- Side Effects: Diarrhea, itching, swelling (edema), rare allergic reactions.
- Contraindications: Hypersensitivity, Leber’s hereditary optic neuropathy.
- Drug Interactions: Certain antibiotics, metformin, PPIs, and other medications.
- Pregnancy & Breastfeeding: Generally safe.
- Dosage: See detailed dosage section above.
- Monitoring Parameters: B12 levels, complete blood count, potassium levels.
Popular Combinations
Often combined with folic acid, especially in the treatment of megaloblastic anemia and during pregnancy.
Precautions
- General Precautions: Assess B12 levels before starting treatment. Monitor for side effects.
- Specific Populations:
- Pregnant Women: Ensure adequate B12 intake for fetal development.
- Breastfeeding Mothers: Monitor infant for signs of B12 deficiency.
- Children & Elderly: Adjust dosage based on age-specific needs.
- Lifestyle Considerations: A balanced diet is essential, especially for vegetarians and vegans. Smoking and excessive alcohol consumption can interfere with B12 absorption.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Cyanocobalamin?
A: The dosage varies based on the individual’s condition and the route of administration. See the “Dosage” section above for detailed guidelines.
Q2: What are the common side effects of Cyanocobalamin?
A: Common side effects include diarrhea, itching, and swelling.
Q3: What are the serious side effects of Cyanocobalamin?
A: Serious side effects are rare but can include allergic reactions, heart failure, pulmonary edema, and hypokalemia.
Q4: Can Cyanocobalamin be given during pregnancy?
A: Yes, Cyanocobalamin is generally considered safe during pregnancy.
Q5: Can Cyanocobalamin be given during breastfeeding?
A: Yes, Cyanocobalamin is generally safe during breastfeeding.
Q6: What are the contraindications to Cyanocobalamin use?
A: Contraindications include hypersensitivity to cyanocobalamin or cobalt, and Leber’s hereditary optic neuropathy.
Q7: What are the common drug interactions with Cyanocobalamin?
A: Cyanocobalamin can interact with certain antibiotics, metformin, proton pump inhibitors, and other medications.
Q8: What is the role of intrinsic factor in Cyanocobalamin absorption?
A: Intrinsic factor, a protein produced in the stomach, is essential for the absorption of oral cyanocobalamin.
Q9: How is Cyanocobalamin eliminated from the body?
A: It’s primarily eliminated through renal excretion.
Q10: What should be monitored during Cyanocobalamin therapy?
A: Monitor B12 levels, complete blood count, and potassium levels during therapy.
