"States keep mum on where lethal injection drugs are made," is an excellent overview by Wendy N. Davis in the March issue of ABA Journal. Here's the beginning, which starts in Missouri:
Like other states with the death penalty, Missouri is facing a shortage of the lethal injection drug pentobarbital, primarily because its Danish manufacturer won’t allow it to be used in executions.
So when the state initially set an execution date for convicted serial killer Joseph Paul Franklin, officials announced that they would instead inject Franklin with a lethal dose of propofol, the same anesthetic that killed Michael Jackson.
But after the European Union threatened to limit shipments of propofol to the United States, as a protest against capital punishment, Gov. Jay Nixon had to order the state Department of Corrections to devise a different method of execution. A few weeks later, the state decided to use pentobarbital after all, and to obtain it from a compounding pharmacy, a company that manufactures the drug but without the same level of federal oversight as big manufacturers.