A federal judge on Monday refused to change the method of execution that includes a new, unused drug on a convicted Ohio killer, the Columbus Dispatch reported.

Due to a shortage of pentobarbital, which is used for lethal injections, the new drug -- combined of a sedative and painkiller -- will be used on Dennis McGuire, convicted of the rape and fatal stabbing of Joy Stewart in 1989.

In his ruling, Judge Gregory Frost said attorneys for McGuire, 53, failed to prove he would suffer pain, specifically breathing problems known as "air hunger," from the unused method.

"The evidence before this court fails to present a substantial risk that McGuire will experience severe pain," Frost said.

McGuire's lawyers asked the judge to delay the execution as they challenge the two-drug system and said in a Jan. 6 filing that their client with suffer "agony and terror."

"McGuire will experience the agony and terror of air hunger as he struggles to breathe for five minutes after defendants intravenously inject him with the execution drugs," defense attorneys said.

They added that McGuire shows symptoms of sleep apnea, which could make the problem worse.

However, prosecutors displayed evidence that disputed the "air hunger" theory and suggested his plea was requested too late.

"You're not entitled to a pain-free execution," said Thomas Madden, assistant Ohio attorney general.

Ronald Phillips, an inmate on death row, was the first person to be given the new form of lethal injection last year until Governor John Kasich delayed his execution to determine whether or not Phillips could donate his organs to family members.

The supply of the original drug used for executions became sparse after it's manufacturer put it off limits for executions.