(CNN) -- An Alabama death row inmate who challenged the constitutionality of the state's execution procedures coughed and heaved for about 13 minutes during his execution by lethal injection Thursday night, AL.com reported.

The inmate, Ronald B. Smith, was among death row inmates nationwide who have challenged states' recent changes to drug rosters used in executions -- changes that came after manufacturers restricted access to traditionally used drugs.

Smith, convicted in Alabama of a 1994 robbery and murder, was pronounced dead at 11:05 p.m. CT, 34 minutes after the execution began at the Holman Correctional Facility in Atmore, according to AL.com, whose reporter Kent Faulk was present.

During a 13-minute span toward the start of the process, Smith "appeared to be struggling for breath and heaved and coughed and clenched his left fist," and his left eye appeared to be slightly open at times, AL.com reported.

These things appeared to have happened after the first of three drugs was administered, according to the report.

Alabama requires a corrections officer to check whether the inmate is unconscious before the next two drugs are given. Smith was tested twice, in part by pinching him; he heaved, coughed and gasped after the first test, and his right arm and hand moved after the second test, according to AL.com.

Eventually, two other drugs were given to stop his breathing and his heart, according to AL.com.

After the execution, Faulk asked Alabama Department of Corrections Commissioner Jeff Dunn about Smith's apparent struggle for breath during the process.

"There will be an autopsy that will be done on Mr. Smith, and if there were any irregularities or anything, then that would be shown or borne out in the autopsy," Dunn said.

Bob Horton, a spokesman for the Department of Corrections, said the 30 minutes it took Smith to die is within the typical time frame of the state's death row protocol.

Horton, who witnessed the execution, confirmed that Smith periodically coughed through the first 13 minutes of the procedure but there was no indication that he was conscious.

Execution's delay, and Smith's drug argument

Smith was convicted in Alabama in the 1994 death of Casey Wilson, a convenience store clerk.

Smith's execution came only after the US Supreme Court twice delayed it Thursday, but then allowed it to proceed, amid a flurry of last-minute motions and orders.

His lawyers had employed several arguments against the execution this year. An April lawsuit alleged Alabama's relatively new execution protocol would subject him to tortuous pain and violate the Constitution's prohibition of cruel and unusual punishment.

The argument is similar to those from other condemned inmates in recent years, stemming in part from several US executions in 2014 -- after states altered their drug protocols -- in which witnesses said inmates appeared to suffer.

Lethal injection traditionally required a three-drug cocktail: The first (sodium thiopental or pentobarbital) put the prisoner to sleep; the second (pancuronium bromide) brought on paralysis; and the final agent (potassium chloride) stopped the heart.

But manufacturers and European countries started withholding pentobarbital and other drugs this decade, saying they didn't want them used in executions. Alabama and other states turned to midazolam as an alternative to the anesthetic.

Pfizer moves to block its drugs from use in executions

Smith's lawyers argued that midazolam is just a sedative, not a barbituate that would more reliably render him unconscious like pentobarbital. They argued that would expose him to "horrific pain" from the heart-stopping agent, potassium chloride.

"Because of the way midazolam works in the human body, it could sedate an individual to the point where he was incapable of communication that he was in pain while doing nothing to suppress the experience of pain," the lawsuit reads.

Horton said Friday that Smith was administered midazolam as a sedative for the first part of the protocol.

Lawsuits filed against states

A number of lawsuits have been filed alleging lethal injections using alternatives like midazolam caused undue suffering.

In 2014, several executions, all employing midazolam, were widely considered botched. In Ohio, Dennis McGuire gasped and convulsed for 10 minutes before dying. In Arizona, Joseph Woodsnorted and gulped for air as he died over a period of two hours. And in Oklahoma, Clayton Lockett writhed for 43 minutes before succumbing to a heart attack.

After each of those cases, states issued holds on capital punishment while the processes were reviewed.

in June 2015, the Supreme Court upheld the use of midazolam in executions in a 5-4 ruling.

Ohio said it would go back to using thiopental sodium instead of a midazolam-hydromorphone combination, but then delayed executions until 2017 because it was having trouble getting the necessary drugs.

Smith's other arguments

Smith's lawyers also tried other arguments, including that a jury had sentenced him not to death, but life in prison without parole. The death sentence came from the trial court, which overrode the jury's verdict.

Smith argued that he should be given life without parole, in part because Alabama's sentencing scheme is similar to that of Florida's, which the Supreme Court struck down in an opinion called Hurst v. Florida.

Lawyers for Alabama stressed that Hurst v. Florida has no retroactive application to Smith.

Ultimately, no court stopped Smith's execution.

The Supreme Court re-instated the death penalty in 1976 after having suspended it earlier in the 1970s.

Lethal injection is the primary means of execution in all 31 death-penalty states. Since 1976, 1,442 people have been executed in the United States -- all but 175 by lethal injection, according to the Death Penalty Information Center.