Piridoxilate-Induced Calcium Oxalate Nephrolithiasis: A Nation-wide Epidemiologic Evaluation of Incidence

Piridoxilate is a drug consisting of an equimolar combination of glyoxylate and pyridoxine which is used in France and in some other European countries for the treatment of coronary disease. For this purpose, it is administered in tablet form containing 150 mg of piridoxilate and 50 mg of Pentaerythrityl-tetranitrate (MyocorilR). It is also used to treat peripheral arteriopathy and, in this situation, is given in tablets containing 100 mg of piridoxilate (Glyo-6R). Glyoxylate decreases oxygen consumption by myocytes, Pyridoxine is combined with it in order to prevent excessive conversion of glyoxylate to the end-product oxalate by enhancing the pyridoxine-dependent metabolic pathway from glyoxylate to glycine (1). The recommended dose of piridoxilate is 600 mg/day, which corresponds to 165 mg of glyoxylate and 435 mg of pyridoxine. The drug had been in use for about 10 years in France when it came to our attention that a number of patients referred to us with kidney stones had been receiving long-term treatment with this drug (2). A growing number of cases of rapidly-recurrent nephrolithiasis with stones made of calcium oxalate were subsequently observed by us (3) and others (4). Several additional cases recorded in the past two years have increased our series to a total of 36 patients. This unexpected frequency prompted us to undertake a nation-wide epidemiologic evaluation of the incidence of this new drug-induced metabolic nephrolithiasis.