Vitamin B6
Vitamin B6 - General Information
The 4-methanol form of vitamin B 6 which is converted to pyridoxal phosphate which is a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid. Although pyridoxine and Vitamin B 6 are still frequently used as synonyms, especially by medical researchers, this practice is erroneous and sometimes misleading (EE Snell; Ann NY Acad Sci, vol 585 pg 1, 1990). [PubChem]
Pharmacology of Vitamin B6
Vitamin B6 (pyridoxine) is a water-soluble vitamin used in the prophylaxis and treatment of vitamin B6 deficiency and peripheral neuropathy in those receiving isoniazid (isonicotinic acid hydrazide, INH). Vitamin B6 has been found to lower systolic and diastolic blood pressure in a small group of subjects with essential hypertension. Hypertension is another risk factor for atherosclerosis and coronary heart disease. Another study showed pyridoxine hydrochloride to inhibit ADP- or epinephrine-induced platelet aggregation and to lower total cholesterol levels and increase HDL-cholesterol levels, again in a small group of subjects. Vitamin B6, in the form of pyridoxal 5'-phosphate, was found to protect vascular endothelial cells in culture from injury by activated platelets. Endothelial injury and dysfunction are critical initiating events in the pathogenesis of atherosclerosis. Human studies have demonstrated that vitamin B6 deficiency affects cellular and humoral responses of the immune system. Vitamin B6 deficiency results in altered lymphocyte differentiation and maturation, reduced delayed-type hypersensitivity (DTH) responses, impaired antibody production, decreased lymphocyte proliferation and decreased interleukin (IL)-2 production, among other immunologic activities.
Vitamin B6 for patients
Vitamin B6 Interactions
Interactions for Vitamin B6 (Pyridoxine):
Amiodarone: Concomitant use of vitamin B6 and amiodarone may enhance amiodarone-induced photosensitivity reactions. Doses of vitamin B6 greater than 5-10 milligrams/day should be avoided by those taking amiodarone.
Carbamazepine: Chronic use of carbamazepine may result in a significant decrease in plasma pyridoxal 5'-phosphate levels.
Cycloserine: Cycloserine may react with pyridoxal 5'-phosphate to form a metabolically inactive oxime, which may result in a functional vitamin B6 deficiency.
Ethionamide: The use of ethionamide may increase vitamin B6 requirements.
Fosphenytoin: High doses of vitamin B6 may lower plasma levels of phenytoin. Fosphenytoin is a prodrug of phenytoin.
Hydralazine: The use of hydralazine may increase vitamin B6 requirements.
Isoniazid: (isonicotinic acid, INH). Isoniazid reacts with pyridoxal 5'-phosphate to form a metabolically inactive hydrazone, which may result in functional vitamin B6 deficiency.
Levodopa: Concomitant use of levodopa and vitamin B6 in doses of 5 milligrams or more daily may reverse the therapeutic effects of levodopa. Vitamin B6 does not reverse the therapeutic effects of levodopa if levodopa is taken concurrently with the levodopa decarboxylase inhibitor carbidopa. Levodopa is typically administered as a combination product with carbidopa.
Oral contraceptives: The use of oral contraceptives may increase vitamin B6 requirements. This was more the case with the older oral contraceptive agents with high-dose estrogen/progestin. It appears to be less the case with the newer low-dose estrogen/progestin products.
Penicillamine: Penicillamine may react with pyridoxal 5'-phosphate to form a metabolically inactive thiazolidine, which may result in a functional vitamin B6 deficiency.
Phenelzine: Phenelzine may react with pyridoxal 5'-phosphate to yield a metabolically inactive hydrazone compound.
Phenobarbital: High doses of vitamin B6 may lower plasma levels of phenobarbital.
Phenytoin: High doses of vitamin B6 may lower plasma levels of phenytoin.
Theophylline: Theophylline may react with pyridoxal 5'-phosphate leading to low plasma levels of the coenzyme. This may increase the risk of theophylline-induced seizures.
Valproic acid: Chronic use of valproic acid may result in a significant decrease in plasma pyridoxal 5'-phosphate levels.
Vitamin B6 Contraindications
Contraindications for Vitamin B6 (Pyridoxine):
Vitamin B6 is contraindicated in those hypersensitive to any component of a vitamin B6-containing product.
Additional information about Vitamin B6
Vitamin B6 Indication: For the treatment of vitamin B6 deficiency and for the prophylaxis of isoniazid-induced peripheral neuropathy.
Mechanism Of Action: Vitamin B6 is the collective term for a group of three related compounds, pyridoxine (PN), pyridoxal (PL) and pyridoxamine (PM), and their phosphorylated derivatives, pyridoxine 5'-phosphate (PNP), pyridoxal 5'-phosphate (PLP) and pyridoxamine 5'-phosphate (PMP). Although all six of these compounds should technically be referred to as vitamin B6, the term vitamin B6 is commonly used interchangeably with just one of them, pyridoxine. Vitamin B6, principally in the form of the coenzyme pyridoxal 5'-phosphate, is involved in a wide range of biochemical reactions, including the metabolism of amino acids and glycogen, the synthesis of nucleic acids, hemogloblin, sphingomyelin and other sphingolipids, and the synthesis of the neurotransmitters serotonin, dopamine, norepinephrine and gamma-aminobutyric acid (GABA).
Drug Interactions: Not Available
Food Interactions: Not Available
Generic Name: Pyridoxine
Synonyms: Vitamin B6; Adermin hydrochloride; Adermine hydrochloride; Aderomine hydrochloride; Pyridoxine HCl; Pyridoxine Chloride; Pyridoxin hydrochloride; Pyridoxine hydrochloride; Pyridoxine hydrogen chloride; Pyridoxinium Chloride; Pyridoxinum Hydrochloricum; Pyridoxol hydrochloride; PN; Hexabione hydrochloride; Pyridoxamine
Drug Category: Anti-inflammatory Agents; Essential Vitamin; Vitamins (Vitamin B Complex)
Drug Type: Small Molecule; Nutraceutical; Approved
Other Brand Names containing Pyridoxine: Aderoxine; Alestrol; Becilan; Beesix; Benadon; Bonasanit; Campoviton 6; Gravidox; Hexa-Betalin; Hexavibex; Hexermin; Hexermine; Hexobion; Hydoxin; Nestrex; Pydox; Pyridipca; Pyridox; Pyridoxine-HCl Microencapsulated; Rodex TD; Tex Six T.R.; Vitamin B6; Vitaped;
Absorption: The B vitamins are readily absorbed from the gastrointestinal tract, except in malabsorption syndromes. Pyridoxine is absorbed mainly in the jejunum.
Toxicity (Overdose): Oral Rat LD50 = 4 gm/kg. Toxic effects include convulsions, dyspnea, hypermotility, diarrhea, ataxia and muscle weakness.
Protein Binding: 22%
Biotransformation: Hepatic.
Half Life: 15-20 days
Dosage Forms of Vitamin B6: Tablet Oral
Solution Intramuscular
Liquid Intramuscular
Solution / drops Oral
Chemical IUPAC Name: 4,5-bis(hydroxymethyl)-2-methylpyridin-3-ol
Chemical Formula: C8H11NO3
Pyridoxine on Wikipedia: https://en.wikipedia.org/wiki/Pyridoxine
Organisms Affected: Humans and other mammals
