COBALIN-H

Indications

• Vitamin B12 deficiency
• Pernicious anemia

Mechanism of action

Hydroxocobalamin functions by acting as a cofactor for enzymatic reactions involving vitamin B12. Methylcobalamin, one of its active forms, is crucial for the conversion of homocysteine to methionine, which is vital for DNA methylation and amino acid metabolism. 5-Deoxyadenosylcobalamin is involved in the conversion of L-methylmalonyl-CoA to succinyl-CoA, a key step in energy extraction from fats and proteins. Furthermore, hydroxocobalamin can bind cyanide ions, forming a stable and non-toxic derivative, cyanocobalamin, which is excreted via urine.

Pharmacodynamics

Hydroxocobalamin plays a significant role in various biological systems. It is essential for the synthesis of myelin and the maintenance of healthy red blood cells. Its deficiency can lead to neurological lesions and impaired red blood cell formation. The compound also supports the metabolism of carbohydrates and fats, aids in DNA synthesis, and is involved in cell replication and hematopoiesis. Hydroxocobalamin's pharmacological effects contribute to overall growth and maintenance of metabolic functions in the body.

Pharmacokinetics

Hydroxocobalamin is administered via intramuscular injection or orally. It is well-absorbed when administered intramuscularly, allowing for sustained release into the bloodstream. The half-life of hydroxocobalamin is prolonged, enabling it to maintain adequate serum levels over extended periods. Hydroxocobalamin is primarily excreted through the kidneys, and its metabolites are eliminated in the urine. As a water-soluble vitamin, it has a low potential for toxicity, though excessive doses may lead to adverse effects.

Adverse effects

• Abdominal distension
• Decreased appetite
• Flatulence
• Nausea

Interactions

• Folic acid may interact with hydroxocobalamin for the treatment of megaloblastic anaemia.

Precautions

• Should never be given alone for pernicious anaemia.
• Caution in patients with vitamin B12 deficiency associated with degeneration of the spinal cord.

Pregnancy

Hydroxocobalamin is considered safe for use during pregnancy for the treatment of vitamin B12 deficiency; it plays a role in preventing neural tube defects.

Breast-feeding

Hydroxocobalamin is generally safe during breastfeeding as it is a form of vitamin B12, which is essential for infant growth.

Storage

Store in a cool, dry place, away from direct sunlight. Do not freeze.

Formulations

• Tablet
• Oral solution
• Solution for injection

Mechanism of action

Vitamin B12 exists in four major forms referred to collectively as cobalamins; deoxyadenosylcobalamin, methylcobalamin, hydroxocobalamin, and cyanocobalamin. Two of these, methylcobalamin and 5-deoxyadenosyl cobalamin, are primarily used by the body. Methionine synthase needs methylcobalamin as a cofactor. This enzyme is involved in the conversion of the amino acid homocysteine into methionine. Methionine in turn is required for DNA methylation. 5-Deoxyadenosyl cobalamin is a cofactor needed by the enzyme that converts L-methylmalonyl-CoA to succinyl-CoA. This conversion is an important step in the extraction of energy from proteins and fats. Furthermore, succinyl CoA is necessary for the production of hemoglobin, the substances that carries oxygen in red blood cells. Hydroxocobalamin is a complexation agent that acts by direct binding of the cyanide ions, resulting in cyanocobalamin which is a highly stable, nontoxic compound that is excreted in the urine. In addition, increased blood pressure observed in some healthy subjects of the phase I clinical study and results of a non-clinical study performed in anesthetized rabbits suggest an interference of hydroxocobalamin with the NO system. VITAMIN B12 IS IMPLICATED IN PROTEIN SYNTH THROUGH ITS ROLE IN SYNTH OF AMINE ACID METHIONINE... /COBALAMINS/ COENZYME B12 IS REQUIRED FOR HYDROGEN TRANSFER & ISOMERIZATION WHEREBY METHYLMALONATE IS CONVERTED TO SUCCINATE, THUS INVOLVING COBALAMIN IN BOTH FAT & CARBOHYDRATE METABOLISM. ... METHYLCOBALAMIN IS REQUIRED FOR CONVERSION OF HOMOCYSTEINE TO METHIONINE IN MAMMALS. /COBALAMINS/

Pharmacodynamics

Hydroxocobalamin is a synthetic, injectable form of Vitamin B12. Hydroxocobalamin is actually a precursor of two cofactors or vitamins (Vitamin B12 and Methylcobalamin) which are involved in various biological systems in man. Vitamin B12 is required for the conversion of methylmalonate to succinate. Deficiency of this enzyme could therefore interfere with the production of lipoprotein in myelin sheath tissue and so give rise to neurological lesions. The second cofactor, Methylcobalamin, is necessary for the conversion of homocysteine to methionine which is essential for the metabolism of folic acid. Deficiency of tetrahydrafolate leads to reduced synthesis of thymidylate resulting in reduced synthesis of DNA which is essential for cell maturation. Vitamin B12 is also concerned in the maintenance of sulphydryl groups in reduced form, deficiency leading to decreased amounts of reduced SH content of erythrocytes and liver cells. Overall, vitamin B12 acts as a coenzyme for various metabolic functions, including fat and carbohydrate metabolism and protein synthesis. It is necessary for growth, cell replication, hematopoiesis, and nucleoprotein as well as myelin synthesis. This is largely due to its effects on metabolism of methionine folic acid, and malonic acid.