Pyridoxine hydrochloride, or vitamin B6, is a member of the B complex family. This vitamin is found in high quantities in foods such as bananas, sardines, chicken spinach and avocados, according to the website dietbites.com. Pyridoxine hydrochloride is necessary for proper nerve function and for metabolizing nutrients. The essential fatty acid linoleic acid requires this vitamin in order to be digested and assimilated, and release of glycogen from the liver occurs with the help of vitamin B6. Because it is water soluble, overdosing is rare; however, certain adverse reactions occur in some situations.
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Excessive intake of pyridoxine hydrochloride can occur from overuse of vitamin supplements. At levels of 500 mg per day, and in some rare cases less than 500 mg per day, sensory neuropathy in the arms and legs has been observed, according to the National Institutes of Health Office of Dietary Supplements. Peripheral neuropathy is characterized by changes in sensation that may include, burning or freezing sensations, tingling, numbness or the feeling of wearing a glove or a sock. Usually, the neuropathy associated with vitamin B6 overdose is not permanent and resolves when the vitamin supplementation is discontinued.
Long term chronic use of high doses of pyridoxine hydrochloride has been associated with ataxia, or lack of ability to coordinate muscle movements, in particular those having to do with walking. A June, 2010 study published in the journal "La revue de Medicine Interne" discussed a case of a 62-year-old gentleman with several months' history of chronic ataxia due to demyelination of the nerves that was resistant to corticosteroid treatment. He was found to have high serum levels of vitamin B6 following several years of supplementation.
Some medications can interfere with metabolism of pyridoxine hydrochloride and lead to deficiency syndromes. The tuberculosis medications isoniazid and cycloserine, pencillamine--a metal chelator--and L-dopa, which is used for Parkinson's disease, all cause a functional deficiency of vitamin B6 by binding to it and making it unavailable for absorption, according to the Linus Pauling Institute. This deficiency is alleviated by taking extra quantities of the vitamin in supplement form to make up for the drug interference effect.
Pyridoxine Hydrochloride Effects on Drugs
While some drugs can interfere with absorption of vitamin B6, the reverse effect of the vitamin interfering with activity of medications can occur, as well. The anticonvulsants phenobarbitol and phentoin have reduced effects in the presence of high concentrations of pyridoxine hydrochloride, and L-dopa is similarly affected, according to the January, 1999 British Journal of Nutrition.