Mecopen

Approved Indications:

• Peripheral Neuropathy: Treatment of diabetic, alcoholic, or drug-induced neuropathy.
• Megaloblastic Anemia: Due to vitamin B12 deficiency.
• Vitamin B12 Deficiency: From dietary deficiency, malabsorption (e.g., post-gastrectomy, chronic gastritis), or in elderly patients.
• Subacute Combined Degeneration of the Spinal Cord: Resulting from chronic B12 deficiency.

Clinically Accepted Off-Label Uses:

• Optic Neuropathy: Supportive therapy in nutritional or toxic optic nerve damage.
• Cognitive Impairment: Investigated in elderly patients with mild cognitive dysfunction or memory loss.
• Chronic Fatigue Syndrome or General Weakness: As a supportive supplement.
• Amyotrophic Lateral Sclerosis (ALS): Used as adjunctive therapy in some countries (e.g., Japan).

Route: Oral, Intramuscular (IM), or Intravenous (IV)

Adults:

• Peripheral Neuropathy:
• Oral: 500 mcg – 1,500 mcg/day in 1–3 divided doses
• IM/IV: 500 mcg 3 times per week for 2–4 weeks, followed by maintenance based on clinical response
• Megaloblastic Anemia or B12 Deficiency:
• IM/IV: 500 mcg to 1,000 mcg daily or every other day for 1–2 weeks, then 500 mcg monthly as maintenance
• ALS (Adjunctive therapy):
• IV: Up to 25 mg three times weekly (under medical supervision)

Elderly:

• No dose adjustment needed. Oral absorption may be reduced in atrophic gastritis or hypochlorhydria.

Pediatric:

• Not routinely used unless prescribed by a specialist.
• Typical dose (if indicated): 250–500 mcg IM/IV weekly.

Renal Impairment:

• No dose adjustment necessary.

Hepatic Impairment:

• No specific adjustment required.

Duration: Based on the underlying condition. Long-term or lifelong therapy may be required in chronic or irreversible deficiency states.

Mecobalamin is a neurologically active, coenzyme form of vitamin B12. It functions as a cofactor for methionine synthase, which catalyzes the methylation of homocysteine to methionine—a key step in DNA synthesis and in maintaining myelin integrity. By supporting methylation reactions and promoting synthesis of nucleic acids, proteins, and lipids, mecobalamin facilitates axonal regeneration and nerve repair. It acts directly on the nervous system to enhance nerve conduction and regeneration, making it particularly effective in treating neuropathies.

• Absorption: Well absorbed in the terminal ileum via an intrinsic factor-mediated mechanism; parenteral routes bypass this.
• Bioavailability: Low (~5–10%) orally; nearly 100% via injection.
• Distribution: Widely distributed to the liver, bone marrow, and nervous tissue; crosses the blood-brain barrier.
• Metabolism: Minimal hepatic metabolism; active as administered.
• Half-life: 6–15 hours (may be prolonged in deficient individuals).
• Excretion: Primarily excreted in the urine; a portion is recycled via the enterohepatic circulation.

• Pregnancy Category: Category C (international classification); no adequate human studies, but animal studies show no risk. Used when clinically necessary.
• Lactation: Excreted into breast milk in small amounts. No known harm to the infant when used at standard doses.
• Recommendation: Safe when clearly indicated. Monitor both mother and infant during use.

• Primary Class: Vitamin B12 Supplement
• Subclass: Coenzyme form of Vitamin B12 (Methylated cobalamin)

• Known hypersensitivity to mecobalamin or other forms of cobalamin
• Hereditary optic nerve atrophy (Leber’s disease)
• Hypokalemia uncorrected (during rapid hematologic correction)
• Functional vitamin B12 deficiency due to lack of intrinsic factor when oral route is used

• Uncorrected Hypokalemia: Rapid correction of anemia can precipitate hypokalemia.
• Masking of B12 Deficiency: Folic acid supplementation may mask underlying B12 deficiency—monitor both.
• Chronic Use Monitoring: Long-term users should have periodic serum B12 assessments.
• Allergic Reactions: Hypersensitivity reactions, including rash or rarely anaphylaxis, may occur.
• Leber’s Disease: May cause severe optic nerve damage in affected individuals—avoid use.

Common:

• Gastrointestinal: Nausea, diarrhea, loss of appetite
• CNS: Headache, dizziness
• Injection Site: Pain, redness, mild irritation

Rare but Serious:

• Hypersensitivity reactions (rash, urticaria, anaphylaxis)
• Hypokalemia (especially in rapid anemia correction)
• Acneiform or papular eruptions

Onset: Usually within a few hours to days
Severity: Mild and self-limiting in most cases; serious effects are rare

• Chloramphenicol: May antagonize hematologic response to mecobalamin.
• Metformin: Long-term use may reduce B12 absorption—monitor levels.
• Proton Pump Inhibitors / H2 Blockers: Reduce gastric acid needed for B12 absorption, impairing oral mecobalamin uptake.
• Nitrous Oxide: Inactivates B12 and may exacerbate deficiency.
• Alcohol (chronic use): Reduces B12 absorption over time.

• Diabetic Neuropathy: Still widely recommended in guidelines as first-line or adjunctive therapy.
• ALS Research: High-dose mecobalamin has shown promise in delaying disease progression in ALS (in select studies).
• Updated Nutritional Protocols: Emphasize mecobalamin use in vegans, elderly, and post-bariatric surgery patients with long-term deficiency risk.

• Temperature: Store at 20°C to 25°C (68°F to 77°F)
• Humidity: Protect from excess moisture
• Light: Store in a dark place; shield from direct light
• Handling Instructions:
• Do not freeze
• Injectable solutions should be used immediately after opening
• Oral forms should be kept in original container with desiccant if included
• No reconstitution required unless provided as powder