NEUROTAB

Description

PHARMACOLOGICAL PROPERTIES:

Pharmacodynamic properties:

Pharmacotherapeutic group: Cobalamin Derivative

Mechanism of action

Mecobalamin is the neurologically active form of vitamin B12 and occurs as a water soluble vitamin in the body. It is a cofactor in the enzyme methionine synthase, which functions to transfer methyl groups for the regeneration of methionine from homocysteine. In anaemia, it increases erythrocyte production by promoting nucleic acid synthesis in the bone marrow and by promoting maturation and division of erythrocytes.

Pharmacokinetic properties:

Absorption

Orally administered vitamin B12 binds to intrinsic factor (IF) during its transport through the stomach. The separation of Vitamin B12 and IF occurs in the terminal ileum when calcium is present, and vitamin B12 is then absorbed into the gastrointestinal mucosal cells. It is then transported by transcobalamin binding proteins. Passive diffusion through the intestinal wall can occur, however, high doses of vitamin B12 are required in this case (i.e. >1 mg). After the administration of oral doses less than 3 mcg, peak plasma concentrations are not reached for 8 to 12 hours, because the vitamin is temporarily retained in the wall of the lower ileum.

Distribution

Cobalamin is distributed to tissues and stored mainly in the liver and bone marrow.

Metabolism

Vitamin B12 or cyanocobalamin obtained from food is initially bound by haptocorrin, a protein found in the saliva with high affinity for B12. This forms a haptocorrin-B12 complex. Cyanocobalamin passes through the stomach and is protected from acid degradation due to its binding to haptocorrin. In the duodenum, pancreatic proteases release cobalamin from the haptocorrin-B12 complex and from other proteins containing protein-bound B12 that have been ingested. Following this, the binding of cobalamin to a second glycoprotein, intrinsic factor, promotes its uptake by terminal ileum mucosal cells by a process called cubilin/AMN receptor-mediated endocytosis. After absorption into enterocytes, intrinsic factor is broken down in the lysosome, and cobalamin is then released into the bloodstream. The transporter ABCC1, found in the basolateral membrane of intestinal epithelial and other cells, exports cobalamin bound to transcobalamin out of the cell. Cyanocobalamin then passes through the portal vein in the liver, and then reaches the systemic circulation. The active forms of cyanocobalamin are Methylcobalamin and adenosylcobalamin.

Elimination

This drug is partially excreted in the urine. According to a clinical study, approximately 3-8 mcg of vitamin B₁₂ is secreted into the gastrointestinal tract daily via the bile. In patients with adequate levels of intrinsic factor, all except approximately 1 mcg is reabsorbed. When vitamin B₁₂ is administered in higher doses that saturate the binding capacity of plasma proteins and the liver, the unbound vitamin B₁₂ is eliminated rapidly in the urine. The body storage of vitamin B₁₂ is dose-dependent.

THERAPEUTIC CLASS: Vitamin B₁₂  

CLINICAL PARTICULARS:

Therapeutic Indication:

• It is used to treat anemia, Alzheimer’s disease, peripheral neuropathy, diabetic neuropathy, rheumatoid arthritis, and probably amyotrophic lateral sclerosis.

Posology and method of Administration:

Posology:

1500 mcg once or twice daily, or as recommended by a physician.

Method of administration

For oral administration:

The tablet should be placed on tongue, let it dissolve and swallow the residue.

Missed Dose:

If one dose is missed, this dose should be omitted and the next dose should be taken at the usual time with a meal. Do not take a double dose to make up for a forgotten dose.

CONTRAINDICATIONS:

• Hypersensitivity reaction
• Suicidal tendency, heart failure, depression, glaucoma
• Dialysis, Renal Failure ,Renal impairment
• Medicines that reduce stomach acid, such as cimetidine, omeprazole, lansoprazole, Nexium, Prevacid, Prilosec, Zantac

SIDE EFFECTS:

• Nausea, vomiting, diarrhea, and loss of appetite
• Allergic reaction, such as hives, difficulty breathing, or swelling of the face, lips, tongue, or throat.
• Dizziness and fatigue

SPECIAL WARNINGS AND PRECAUTIONS FOR USE:

• The use of Mecobalamin in deficiency states or to treat any medical condition requires medical supervision.
• A typical dose as nutritional supplements used by pregnant woman and nursing mothers is 12 micrograms daily.
• Pregnant women and nursing mothers should only use doses higher than this if recommended by their physicians. Administration of doses greater than 10 micrograms daily may produce a hematological response in those with anemia secondary to folate deficiency.

OTHER MEDICINES AND METHYLCOBALAMIN TABLETS:

• Cholestyramine: Cholestyramine may decrease the enterohepatic reabsorption of Mecobalamin.
• Colchicine: Colchicine may cause decreased absorption of Mecobalamin.
• Colestipol: Colestipol may decrease the enterohepatic Reabsorption of Mecobalamin.

PREGNANCY AND BREAST-FEEDING

Pregnancy: Methylcobalamine is compatible in pregnancy.

Breast-feeding: Methylcobalamine is compatible in breast-feeding.

DRIVING AND USING MACHINES

There is no effect of Methylcobalamine in driving and using machines.

OVER DOSE:

• Allergic reaction, such as hives, difficulty breathing, or swelling of the face, lips, tongue, or throat.