Aminopyrine (N,N-Dimethyl-13C2) is used in [13C]??aminopyrine breath test ([13C]??ABT) to measure the global activity of cytochrome P 450 in vivo and is a sensitive indicator of liver metabolic dysfunction. It is a labelled analog of aminopyrine , which has been used as an analgesic, antipyretic and anti-??inflammatory drug, but is also associated with agranulocytosis.