Metabolic Studies of Pyridoxamine (Vitamin B-6) Metabolism in Rats

Pyridoxamine (PM), a metabolic isomer of vitamin B6, has been studied as an agent to reduce/prevent diabetic complications, based upon its ability to prevent formation of advanced glycation end-products and act as an anti-oxidant (Voziyan et al., Cell. Mol. Life Sci. 62:1671,2005). As a preliminary study determining effect of PM on bone collagen matrix in diabetic rats, Sprague-Dawley rats were given subcutaneous saline (control), 50 mg/kg, or 100 mg/kg pyridoxamine; plasma and urine samples were collected over 24 hours. Samples were analyzed by HPLC to quantitate vitamers of vitamin B6 (PLP, 4PA, PL), as well as PM and pyridoxamine-5\u27-phosphate. Urine samples were also analyzed for 4PA, and also PM and N-methylpyridoxamine, to determine if rats, like dogs, are able to methylate pyridoxamine (Ericson et al., Bioorg.Med.Chem.Lett. 18:1845 2008). Data were analyzed using the WINSAAM modeling program, and the plasma half life of PM in rats receiving 50 mg/kg was calculated at 1.43 hours; the half-life in rats receiving 100 mg/kg was calculated to be 1.6 hrs. Supported by NIH grant R01 AR 047838 (DBB)