Because aminopyrine is metabolized by the cytochrome P-450 enzymes in the liver, measuring the rate at which a patient exhales labeled CO2CO sub 2

Due to its potential to cause fatal bone marrow suppression, the U.S. Food and Drug Administration and regulatory bodies in countries like France, Japan, and India suspended its medical use. Despite these bans, it still surfaces in some parts of the developing world. 🔬 Evolution into a Diagnostic Tool

While it fell out of favor as a direct therapeutic agent, aminopyrine found a massive secondary life as a non-invasive tool in biomedical diagnostics:

Scientists synthesized a version of the drug labeled with carbon isotopes (