Pyridoxine Deficiency

To the Editor.  —The recent report in the Archives (1981;141:1713-1714) by Sullivan et al of D-penicillamine-induced pyridoxine-responsive sideroblastic anemia is a valuable contribution to the recognition of medicinal-nutritional interactions. It emphasizes the potential of D-penicillamine to cause pyridoxine deficiency, as has also been noted with isoniazid,¹ ethionamide,² and cycloserine.³ L-Penicil-lamine has been recognized to produce laboratory and clinical evidence of pyridoxine deficiency,⁴ either by binding with pyridoxine to form a thiazolidine compound^5,6 or through inhibition of pyridoxine kinase.⁷ The latter enzyme is necessary for production of the active coenzyme, pyridoxal-5-phosphate.Less potent than its L isomer,^4,8 D-penicillamine has been rarely reported to induce clinical pyridoxine deficiency,^9-11 generally manifested as seizures or peripheral neuropathy. Biochemical evidence of pyridoxine deficiency, however, is more common.^9,12 In view of the observation of Gibbs and Walshe⁹ that 13 of 32 patients experienced biochemical evidence of