Veriben B12

Mechanism of action

Cyanocobalamin serves as a cofactor for methionine synthase and L-methylmalonyl-CoA mutase enzymes. Methionine synthase is essential for the synthesis of purines and pyrimidines that form DNA. L-methylmalonyl-CoA mutase is involved in the degradation of propionate, crucial for fat and protein metabolism. The lack of vitamin B12 results in the accumulation of methylmalonyl CoA, contributing to neurological manifestations. Additionally, it is vital for the synthesis of methionine from homocysteine, and its deficiency can lead to functional folate deficiency, which impacts red blood cell formation.

Pharmacodynamics

Cyanocobalamin corrects vitamin B12 deficiency and alleviates symptoms and laboratory abnormalities associated with pernicious anemia, such as megaloblastic indices, gastrointestinal lesions, and neurological damage. It is essential for growth, cell reproduction, hematopoiesis, nucleoprotein, and myelin synthesis. The drug significantly impacts fat and carbohydrate metabolism, as well as protein synthesis. Rapidly dividing cells, such as those in the bone marrow, have a high demand for vitamin B12. Parenteral administration of cyanocobalamin can quickly reverse the anemia and gastrointestinal symptoms of vitamin B12 deficiency, while also preventing the progression of related neurological damage.

Pharmacokinetics

Cyanocobalamin is absorbed in the intestine, primarily in the ileum, via specific transport mechanisms that may be impaired in individuals with intrinsic factor deficiency (as seen in pernicious anemia). Once absorbed, it is widely distributed in body tissues, with significant concentrations found in the liver, kidneys, and heart. The vitamin is stored in the liver, where it can be released into circulation as needed. Cyanocobalamin undergoes conversion to its active forms, methylcobalamin and adenosylcobalamin, which are utilized in various metabolic processes. The elimination half-life is variable, but it is generally excreted via urine as metabolites

Adverse effects

• Abdominal distension
• Decreased appetite
• Flatulence
• Nausea

Interactions

• Folic acid may interact with cyanocobalamin, especially in cases of megaloblastic anemia caused by folate deficiency.

Precautions

• Should not be given alone for pernicious anemia.
• Use caution in patients with Leber's disease, as it may worsen optic atrophy.

Pregnancy

Cyanocobalamin is essential during pregnancy as it helps prevent neural tube defects. It is advised that females of childbearing potential take 5 mg of folic acid daily before conception and throughout pregnancy.

Breast-feeding

Cyanocobalamin is generally considered safe during breastfeeding, but it is advised to monitor the infant for any adverse effects.

Storage

Store in a cool, dry place, away from direct sunlight. Protect from moisture.

Formulations

• Tablet: 1000 micrograms
• Tablet: 500 micrograms
• Tablet: 100 micrograms
• Oral solution: 50 micrograms per ml
• Solution for injection: 1000 micrograms per ml

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

Indications

• Muscle spasticity
• Muscle spasms
• Pain management in musculoskeletal disorders

Dosage

Children: Refer to specific pediatric guidelines or consult a healthcare professional for appropriate dosing.

Adults: Refer to specific clinical guidelines or consult a healthcare professional for appropriate dosing.

Mechanism of action

Diaceturate acts by inhibiting the presynaptic release of acetylcholine at the neuromuscular junction, thereby reducing muscle contraction. This inhibition leads to decreased excitability of motor neurons and relaxation of skeletal muscles.

Pharmacodynamics

The pharmacodynamic profile of diaceturate indicates its ability to produce muscle relaxation through central and peripheral mechanisms. It alters neurotransmitter release and modulates synaptic transmission, leading to decreased muscle tone and increased ease of movement. Its effects can be observed within a short time frame following administration, making it effective for acute muscle spasm relief.

Pharmacokinetics

Diaceturate is typically absorbed rapidly after administration, with peak plasma concentrations achieved within a few hours. It undergoes hepatic metabolism, with its metabolites being excreted primarily through the kidneys. The drug has a relatively short half-life, necessitating multiple doses for sustained effect in clinical use.

Adverse effects

• Nausea
• Vomiting
• Diarrhea
• Dizziness
• Rash

Precautions

• Use with caution in patients with liver impairment
• Monitor for allergic reactions
• Caution in patients with renal impairment

Pregnancy

The safety of diaceturate during pregnancy has not been established. It should only be used if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Caution is advised when using diaceturate in breastfeeding women, as it's unknown if it passes into breast milk.

Storage

Store at room temperature, away from moisture and light. Keep out of reach of children.

Indications

• Trypanosomiasis (sleeping sickness)
• Nagana in livestock
• Infections caused by Trypanosoma brucei
• Infections caused by Trypanosoma congolense

Dosage

Children: Paediatric dosing of diminazene should be derived from the BNF for Children, taking into account the weight and age of the child. Refer to the BNF for Children for specific dosing recommendations.

Adults: The dosage for adults should be determined based on the specific condition and patient factors. Refer to the BNF for accurate dosing guidelines.

Mechanism of action

Diminazene acts by inhibiting the enzyme dihydrofolate reductase, which is crucial for the synthesis of folate in protozoa. This inhibition disrupts the folate metabolic pathway, leading to a decrease in nucleic acid synthesis and ultimately resulting in the death of the protozoan parasites. Additionally, it may interfere with the mitochondrial function of the parasites, further contributing to its antiparasitic effects.

Pharmacodynamics

The pharmacodynamics of diminazene involve its selective action on trypanosomes, with the drug being less toxic to host cells. It has a high affinity for the target enzyme, allowing for effective suppression of protozoan growth. The drug's therapeutic index is favorable, meaning it can effectively treat infections at doses that are relatively safe for the host.

Pharmacokinetics

Diminazene is well-absorbed following parenteral administration. It is widely distributed throughout the body, with a significant volume of distribution. The drug undergoes hepatic metabolism, and its elimination half-life can vary depending on species and individual health. Excretion is primarily via the urine, with metabolites detected in both urine and feces.

Adverse effects

• Anorexia
• Vomiting
• Diarrhoea
• Lethargy
• Neurological signs (e.g., tremors, ataxia)
• Hypersensitivity reactions

Precautions

• Use with caution in animals with hepatic or renal impairment.
• Monitor for signs of toxicity, especially in cases of overdose.

Pregnancy

Safety during pregnancy has not been established; use only if the benefits outweigh the risks.

Breast-feeding

Safety during breastfeeding has not been established; use with caution.

Storage

Store in a cool, dry place away from light. Keep out of reach of children.

Formulations

• Injection solution

Mechanism of action

Vitamin B12 serves as a cofactor for _methionine synthase_ and _L-methylmalonyl-CoA mutase_ enzymes. Methionine synthase is essential for the synthesis of purines and pyrimidines that form DNA. L-methylmalonyl-CoA mutase converts L-methylmalonyl-CoA to _succinyl-CoA_ in the degradation of propionate, an important reaction required for both fat and protein metabolism. It is a lack of vitamin B12 cofactor in the above reaction and the resulting accumulation of methylmalonyl CoA that is believed to be responsible for the neurological manifestations of B12 deficiency. Succinyl-CoA is also necessary for the synthesis of hemoglobin. In tissues, vitamin B12 is required for the synthesis of _methionine_ from homocysteine. Methionine is required for the formation of S-adenosylmethionine, a methyl donor for nearly 100 substrates, comprised of DNA, RNA, hormones, proteins, as well as lipids. Without vitamin B12, tetrahydrofolate cannot be regenerated from 5-methyltetrahydrofolate, and this can lead to functional folate deficiency,. This reaction is dependent on methylcobalamin (vitamin B12) as a co-factor and is also dependent on folate, in which the methyl group of methyltetrahydrofolate is transferred to homocysteine to form _methionine_ and _tetrahydrofolate_. Vitamin B12 incorporates into circulating folic acid into growing red blood cells; retaining the folate in these cells. A deficiency of vitamin B12 and the interruption of this reaction leads to the development of megaloblastic anemia.

Pharmacodynamics

**General effects** Cyanocobalamin corrects vitamin B12 deficiency and improves the symptoms and laboratory abnormalities associated with pernicious anemia (megaloblastic indices, gastrointestinal lesions, and neurologic damage). This drug aids in growth, cell reproduction, hematopoiesis, nucleoprotein, and myelin synthesis. It also plays an important role in fat metabolism, carbohydrate metabolism, as well as protein synthesis. Cells that undergo rapid division (for example, epithelial cells, bone marrow, and myeloid cells) have a high demand for vitamin B12. **Parenteral cyanocobalamin effects** The parenteral administration of vitamin B12 rapidly and completely reverses the megaloblastic anemia and gastrointestinal symptoms of vitamin B12 deficiency. Rapid parenteral administration of vitamin B12 in deficiency related neurological damage prevents the progression of this condition. **Nasal spray effects** In 24 vitamin B12 deficient patients who were already stabilized on intramuscular (IM) vitamin B12 therapy, single daily doses of intranasal cyanocobalamin for 8 weeks lead to serum vitamin B12 concentrations that were within the target therapeutic range (>200 ng/L).

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.