[Evaluation of germanium dioxide neurotoxicity in rats and monkeys]

Toxic side effects of germanium dioxide contained in drugs that promote health, include nephropathy, anemia and peripheral neuropathy. Although the neuropathy, which we are interested in, is believed to occur in the patients taking excessive amounts of germanium dioxide, the pathogenesis of such neuropathy is not well understood. Therefore, we studied whether germanium dioxide causes the degeneration of the peripheral nerve in rats and monkeys. Our results showed that in rats, germanium dioxide administered orally and intraperitoneally, 100 mg/kg per day, 3 days a week for 8 weeks and 400 mg/kg per day, once a week for 8 weeks, respectively, did not produce a degeneration of myelinated fibers in teased fiber preparations and Epon-embedded sections of the peripheral nerve. In two monkeys also, germanium dioxide, administered orally, 30 to 40 mg/kg per day, 5 days a week for 8 months, did not produce a degeneration of myelinated fibers of the sural nerve on biopsy, although our results revealed proteinuria and elevated blood urea nitrogen. Further studies are warranted to elucidate the pathogenesis of germanium dioxide induced neuropathy.