Pyridoxine helps with amino acid and protein metabolism. After being converted into its active form, pyridoxine is essential for proper enzymatic functions Some of these enzymes convert vitamins and minerals into dietary forms. Other enzymes help with lipid metabolism.
The active form of pyridoxine serves as a coenzyme that helps with hemoglobin synthesis, which binds to two sites on hemoglobin in order to increase the protein's ability to bind to oxygen.
After being converted into its active form, pyridoxine serves as a cofactor in the biosynthesis of various neurotransmitters. The active form of pyridoxine helps synthesize serotonin, dopamine, epinephrine, norepinephrine, and GABA.
Isoniazid is a drug given during tuberculosis treatment (refer to the Picmonic on "Isoniazid"). The medication prevents pyridoxine from converting to its active form and may lead to symptoms of deficiency such as peripheral neuritis. Pyridoxine supplementation is administered concurrently with isoniazid to prevent vitamin deficiency.
Poor diet, administration of isonazid, and inborn errors of metabolism may lead to pyridoxine deficiency. Although pyridoxine deficiency is rare in the general population, nearly 30% of alcoholics have pyridoxine deficiency. Symptoms of dietary deficiency include dermatitis, microcytic anemia, peripheral neuritis, convulsions, depression, and confusion. Patients who are pregnant or breast-feeding require increased pyridoxine intake.
Patients experiencing premenstrual syndrome (PMS) may have pyridoxine deficiency. Pyridoxine may be administered in women suffering from PMS symptoms such as breast pain. Vitamin supplementation may help balance hormonal changes and alleviate symptoms of PMS.
Side effects are not typically seen in patients taking low doses of pyridoxine. However, extremely high doses may lead to neurologic injury such as ataxia. Ataxia is characterized by involuntary muscle coordination.
Patients taking high doses of pyridoxine may experience peripheral neuropathy. The condition manifests as numbness of the hands and feet.
Pyridoxine interferes with the anti-Parkinsonian medication levodopa (refer to the Picmonic on "Levodopa/carbidopa (Sinemet)"). Since concurrent administration is contraindicated, patients taking levodopa should be instructed not to take pyridoxine supplementation.
Highly fortified cereals and soy products are good sources of pyridoxine. Noncitrus fruits and starchy vegetables such as white potatoes also provide dietary pyridoxine. Pyridoxine is also found in fish and poultry. Organ meats such as beef liver are especially rich sources of pyridoxine.
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