A. Bendich, M. Cohen
May 1, 1990
Citations
0
Influential Citations
49
Citations
Quality indicators
Journal
Annals of the New York Academy of Sciences
Abstract
The use of pyridoxine hydrochloride (vitamin B6) in very high doses has been associated with certain adverse clinical responses to the vitamin. While some indications for high-dose vitamin usage, such as pyridoxine-dependency homocystinuria, and oxal~sis l -~ have been clinically demonstrated, other proposed uses, such as treatment of carpal tunnel syndrome," premenstrual syndrome (PMS5), and autism6 are more controversial. Increasing clinical use of pyridoxine has resulted in concern about the safety of treatment regimens. Two specific issues that have appeared in the literature are peripheral neuropathy and the use of pharmacologic doses during pregnancy. Previous reviews of pyridoxine neuropathy have indicated that two factors-oral daily dose and duration of intake-are critical to the full assessment of the risk of adverse effects on sensory nerve function. Cohen and Bendich' in 1986 concluded that clinical doses of less than 500 mg/day were safe over periods as long as six years. Schaumberg and Berger' noted that subjects ingesting 500 mg/day did not report symptoms, while daily intake of 7-10 g resulted in neuropathy within two months. In his review, Bassler9 recommended that long-term intake of doses up to 200 mg/day could be considered safe. However, the need for clinical trials to determine the incidence of adverse effects more accurately was stressed by the author. Concern with the teratogenic potential of high-dose pyridoxine largely results from the controversy associated with Bendectin (doxylamine + pyridoxine) use by pregnant women. An earlier review of this subject' did not find any consistent evidence of teratogenicity for pyridoxine. This review updates the preclinical and clinical data on pyridoxine neurotoxicity to determine whether a more quantitative estimate of risk can be derived based on available data. Recent human and animal data showing lack of teratogenicity for pyridoxine are also summarized.