Methylcobalamin is the active, coenzyme form of Vitamin B12, essential for DNA synthesis, red blood cell formation, and neurological function. The 500mcg/ml strength is a high-dose injectable formulation widely used in India for rapid correction of deficiencies and neuropathic conditions. It is a critical cofactor for methionine synthase and L-methylmalonyl-CoA mutase enzymes.
Adult: Deficiency: 500-1000 mcg IM or deep SC, 3 times per week for 2 weeks, then 500-1000 mcg once monthly. Neuropathy: 500 mcg IM or deep SC, 3 times per week or on alternate days for 4-8 weeks. Maintenance: As per deficiency cause.
Note: For intramuscular (IM) or deep subcutaneous (SC) injection only. Avoid IV administration. Rotate injection sites (gluteal, deltoid, thigh). Protect from light. Do not mix with other medications in the same syringe unless compatibility is proven.
Methylcobalamin acts as a coenzyme for two crucial metabolic reactions: 1) Methionine Synthase: Catalyzes the conversion of homocysteine to methionine, which is essential for DNA/RNA synthesis, myelin formation, and neurotransmitter production. 2) L-Methylmalonyl-CoA Mutase: Converts methylmalonyl-CoA to succinyl-CoA, a key step in lipid and carbohydrate metabolism, crucial for neuronal integrity.
Pregnancy: Category A (US FDA). Considered safe. Methylcobalamin crosses the placenta. Recommended daily intake increases in pregnancy. Injectable form can be used to treat deficiency.
Driving: No known effects on driving ability. Dizziness or headache, if experienced, may impair skills.
| Chloramphenicol | May decrease the hematologic response to Methylcobalamin. | Moderate |
| Proton Pump Inhibitors (Omeprazole, Pantoprazole) | Long-term use may reduce B12 absorption from food but does not affect injected Methylcobalamin. | Minor |
| Metformin | Chronic use can reduce serum B12 levels by interfering with absorption. Injectable Methylcobalamin bypasses this interaction. | Moderate |
| Aminoglycosides, Colchicine, Para-aminosalicylic acid | May reduce intestinal absorption of B12. Not relevant for injectable route. | Minor |
| Folic Acid | High doses of folic acid can mask hematological signs of B12 deficiency, potentially allowing neurological damage to progress. Always correct B12 deficiency first. | Major |
Same composition (Methylcobalamin (500mcg/ml)), different brands: