According to the Death Penalty Information Center, a national nonprofit, most states until 2010 used a three-drug combination to execute criminals: an anesthetic; a paralyzing agent and a chemical to stop the heart. But drug shortages and pressure from death-penalty opponents have forced some manufacturers to pull back and that has led some states to seek different ways to carry out death sentences.
Eight states have used a single lethal dose of an anesthetic and five other states have announced they will use that protocol, but have yet to execute anyone. About 20 states have used or planned to use pentobarbital, one of the drugs that was commonly used in the three-drug protocol.
But Ohio announced in September that it, like some other states, had run out of pentobarbital. The state said it will become the first in the nation to try a two-drug protocol, midazolam, a sedative, and hydromorphone, related to morphine.