Tyropanoic acid
Tyropanoic acid and its salt sodium tyropanoate are radiocontrast agents used in cholecystography. Trade names include Bilopaque, Lumopaque, Tyropaque, and Bilopac. This molecule contains three heavy iodine atoms which obstruct X-rays in the same way as the calcium in bones to produce a visible image. After injection it is rapidly excreted into the bile.