Vibee Mechanism of Action

Pharmacology: Pharmacodynamics: Vitamin B₁ is a water-soluble vitamin. The primary functions of thiamin include metabolism of carbohydrates, branched-chain amino acids, maintenance of normal growth, transmission of nerve impulses, and acetylcholine synthesis.
Vitamin B₆ is a coenzyme in the metabolism of amino acids, glycogen, and sphingoid bases and necessary for normal breakdown of proteins, carbohydrates, and fats. Vitamin B₆ is essential to make hemoglobin and helps increase the amount of oxygen carried by hemoglobin. Vitamin B₆ is also involved in maintaining the health of the immune system including maintaining the health of lymphoid organs (thymus, spleen, and lymph nodes) that make white blood cells. Vitamin B₆ maintains normal levels of blood glucose by helping convert stored carbohydrates or other nutrients to glucose. Vitamin B₆ also is needed for the conversion of tryptophan to niacin.
Vitamin B₁₂ is essential to growth, cell reproduction, hematopoiesis, and nucleoprotein and myelin synthesis. In nature, the vitamin B₁₂ is mainly in the 2-deoxyadenosyl(ado) form and methylcobalamin. They are cofactors for the enzyme methylmalonyl CoA mutase and methionine synthase, respectively.
Pharmacokinetics: Absorption: Vitamin B₁ is absorbed by a Na⁺ dependent active, carrier-mediated process at low concentration in the jejunum and by passive diffusion in the jejunum and ileum at high concentration. Maximum oral absorption is 8 to 15 mg/day. Oral absorption may be increased by administering in divided doses with food.
Vitamin B₆ is absorbed by passive diffusion in the jejunum and to a lesser extent in the ileum.
Vitamin B₁₂ is absorbed in the terminal ileum. Its amount of absorption is regulated by intrinsic factor which is secreted by the parietal cells of the stomach. Simple diffusion is responsible for absorption when more than 30 mcg of vitamin B₁₂ is ingested. Bioavailability of oral preparation is approximately 25%. Pancreatic disorders, bacterial overgrowth, intestinal parasites, sprue, and localized damage to ileal mucosa cells can interfere with absorption. In addition to intrinsic factor, GI absorption requires an alkaline pH. In pancreatic disease, it may be necessary to administer the oral vitamin with bicarbonate or give them the vitamin parenterally.
Distribution: Vitamin B₁ is mainly stored in the liver but is also found in the brain, kidney, heart, intestine, lung, spleen, and muscle.
Vitamin B₆ is stored mainly in the liver with lesser amounts in muscle and brain. The total body store of vitamin B₆ is estimated to be about 167 mg. Pyridoxal and pyridoxal phosphate, the principal forms of the vitamin present in blood, are highly protein bound. Pyridoxal crosses the placenta and breast milk.
Vitamin B₁₂ is bound to transcobalamine II, a specific B-globulin carrier protein. It normally carries only 20-60 ng of cobalamin per liter of plasma. And is distributed and stored primary in the liver, bone marrow and placenta by receptor-mediated endocytosis.
Metabolism/Excretion: Vitamin B₁ (exceed) is excreted in the urine both as thiamin acetic acid and metabolites. Approximately 100 mcg/day of thiamin are excreted in the urine with a daily intake of 0.5 mg/1000 kcal with normal renal function, 80% to 96% of an IV dose is excreted in the urine.
Vitamin B₆ is converted to pyridoxal-5-phosphate in the liver and excreted mostly as 4-pyridoxic acid in the urine.
Vitamin B₁₂ from bile and other intestinal secretions are recycled by enterohepatic circulation. If plasma-binding proteins are saturated, excess free vitamin B₁₂ will be excreted in the kidney.