4-Hydroxyantipyrine-d3
4-Hydroxyantipyrine-d3 is the deuterium labeled 4-Hydroxyantipyrine. 4-Hydroxyantipyrine is the major metabolite of Antipyrine, can be as a biodistribution promoter. 4-Hydroxyantipyrine can increase distribution of concentration ratio of Antipyrine in the brain[3].