A 7-day intravenous toxicity study and neurotoxicity assessment of pyridorin in Sprague-Dawley rats
Pyridorin®, a naturally occurring metabolite of vitamin B6 that inhibits and scavenges reactive oxygen species, is being developed as a potential therapeutic for acute kidney injury. An investigational new drug application (IND) was opened for Pyridorin in support of its ongoing oral drug clinical development program. Currently, a Pyridorin intravenous (IV) formulation is being developed for use in surgical patients. To support the IND for Pyridorin, a full battery of nonclinical Good Laboratory Practice compliant studies was performed with no neurological or behavioral signs of toxicity seen following oral or IV administration of pyridoxine dihydrochloride (the active ingredient in Pyridorin). However, excessive ingestion of vitamin B6 has been reported to cause neurotoxic syndrome in humans. Therefore, under Food and Drug Administration recommendation, a 7-day IV study in rats was conducted to further evaluate the drug’s potential to cause neurotoxicity. Blood plasma samples indicated that exposure to pyridoxamine dihydrochloride and its metabolites, pyridoxal, pyridoxine, and 4-pyridoxic acid was linearly dose proportional and independent of gender. At doses of up to 200 mg/kg/day pyridoxine dihydrochloride, no treatment-related effects were seen in rats, providing further evidence for the absence of pyridoxine dihydrochloride-related changes in the nervous system. A no observed adverse effect level of 200 mg/kg/day was identified for this study.