When Danish drug company Lundbeck learned its product was being used for lethal injections, it refused to sell any more to U.S. prisons.
Lundbeck also demanded its American counterparts do the same, The New York Times reported.
Boycotts like this one are forcing states to find new drugs for lethal injections — including ones that haven't been approved for that purpose.
Missouri will be the first-ever state to use the anesthetic propofol in two impending executions, according to the Associated Press.
Propofol — made famous for its role in Michael Jackson's death — hasn't ever been used in a lethal injection and could cause unnecessary pain, opponents argue.
"This is an experiment with a human subject," Richard Dieter, executive director of the Death Penalty Information Center in Washington, told the AP. "This will be sort of a brute force approach where you give them enough and they die."
Other states, like Georgia, have turned to specialty drugmakers that opponents say don't have adequate quality controls, The Times reported.
California and Arkansas have both suspended executions until they can find a replacement for pentobarbital, another drug used frequently in lethal injections. And Texas, America's most active death penalty state, is scheduled to run out in September, the AP reported. The state has at least seven executions before then and has yet to find an alternative.
All 32 states with capital punishment use lethal injection as the primary method of execution, but other options exist such as electrocution or a firing squad in a small number of states.