Pyridoxamine, a form of vitamin B6 found naturally in foods like carrots, walnuts, chicken, and fish, was once sold as a dietary supplement in the United States. In the form of pyridoxamine, the chemical does not act as vitamin B6; it must first be converted into its active form pyridoxal 5-phosphate by one of the body's vitamin salvage pathways. While very similar in its chemical structure to pyridoxine, it does not appear to pose the same risk of causing peripheral neuropathy when high doses are used for a long period of time.
Since several studies indicated that it was more effective than other investigational medicines in preventing the damage to kidney tissues associated with late-stage diabetes, its low incidence of side effects made it an ideal new drug candidate. Although research for developing the vitamin into a treatment for kidney disease has since stalled, in 2009 the United States Food and Drug Administration (FDA) classed pyridoxamine as an investigational drug, banning its sale as a dietary supplement.
Prior to the ban, the vitamin was recommended by some alternative medical practitioners as an anti-aging remedy. This was in partly due to the findings of several studies, which indicated that the compound inhibited the formation of certain free radicals produced when the body burns fat. Some research also suggested that it was a more effective radioprotective agent than the only FDA-approved drug used to protect against ionizing radiation damage. Since aging is believed to be in part due to DNA damage incurred from free radicals and radiation, it is possible that the vitamin may act as a preventative agent.
Pyridoxamine was best known for it's possible ability to prevent the formation of advanced glycation endproducts. Advanced glycation endproducts have been implicated in a number of serious age-related conditions, including atherosclerosis, Alzheimer's disease, liver disease, kidney disease and neuropathy. Binding to cells within nearly every body system, they are believed to exert their pathological effects by enhancing oxidative stress, inducing the secretion of inflammatory compounds, oxidizing low-density lipoproteins — LDL cholesterol, and interfering with vascular dilation and permeability. By reducing AGEs in the bloodstream, it is possible that pyridoxamine may slow the progression of the diseases associated with them. Despite the potential positive effects of pyridoxamine on multifactorial chronic diseases, it will not be available in the United States as a drug until phase IIb and phase III trials have been completed.