James A. Finley/Associated Press

Ohio announced Monday that it plans to put to death a prisoner next month with a two-drug cocktail that has never before been tried by any state for an execution.

On Nov. 14, the state plans to use a lethal combination of Midazolam, a sedative, and Hydromorphone, a painkiller, to execute Ronald Phillips, 40, who was sentenced to death 20 years ago for the rape and murder of 3-year-old Sheila Marie Evans.

Ohio's decision arrives on the heels of an execution that took place in Florida on Oct. 15, where the Sunshine State also used an untried procedure—a three-drug cocktail also including Midazolam—to comply with a death sentence. The execution lasted 14 minutes, or twice what is normally expected with the previous drug of choice.

Ohio, like Florida and Texas, is one of a growing number of death-penalty states scrambling to replace the chemicals it normally relies on to carry out executions. Missouri also planned to use an untested drug—Propofol, an anesthetic that gained notoriety for contributing to Michael Jackson's death—for an execution this month, but the governor prohibited its use, citing concerns it could inflict an unnecessary amount of pain.

"Ohio reviewed all available information from other states, and considered all available options," Ricky Seyfang, a spokeswoman for the state's Department of Rehabilitation and Correction, told National Journal earlier this month. "The combination of Midazolam and Hydromorphone has already been part of Ohio's execution policy since November 2009, when those two drugs were identified for intramuscular injection, as a backup to the intravenous injection." Seyfang did not provide further detail about how the drugs were selected.

Ohio has seen a flurry of changes to its lethal-injection protocol in recent years. Until 2009, the state relied on a three-drug combination that was then standard across most states. In December of that year, Ohio became the first state to adopt a single, lethal dose of sodium thiopental, before again changing its procedure in 2011 to allow for only Pentobarbital, a drug commonly used to euthanize pets, to do the trick. Its one-drug use of Pentobarbital was also a first.

But Danish drug manufacturer Lundbeck, buckling under public pressure in the capital-punishment-free European Union, halted sales of Pentobarbital to the states, and Ohio exhausted its supply of Pentobarbital in September. The state then determined it would consult compounding pharmacies—where prescription drugs are individually crafted to fit a person's medical needs—to secure its Pentobarbital, but updated its execution policy to allow for a backup cocktail—Midazolam and Hydromorphone—in the event Pentobarbital was unavailable.

Compounding pharmacies are lightly regulated and don't want to be publicly identified as places that make drugs used for executions, and it appears Ohio had little luck finding any willing to supply Pentobarbital. Missouri is now also attempting to secure Pentobarbital from compounding pharmacies.

Whether Ohio forges ahead with its untested cocktail, like Florida, or succumbs to public pressure, like Missouri, remains to be seen. But barring an unlikely spate of execution innovation within the medical community, the routes states can walk to fulfill their death sentences are becoming increasingly narrow.