1-Methylxanthine-13C,d3
1-Methylxanthine-13C,d3 is the 13C- and deuterium labeled 1-Methylxanthine. 1-Methylxanthine, a caffeine derivative, is an essential human urinary metabolite of caffeine and theophylline (1,3-dimethylxanthine, TP). 1-Methylxanthine enhances the radiosensitivity of tumor cells.