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LITTLE ROCK, Ark. (AP) — When administered as their manufacturers intend, the three drugs Arkansas could use in lethal injections next week if courts allow the executions to proceed are key products of the pharmaceutical industry. They produce amnesia for patients heading into medical procedures, relax muscles to the point that they don’t interfere with knife-wielding surgeons and regulate heart rhythms in cardiac patients.

Doctors say that, at the large doses that would be given to seven inmates beginning Monday, the midazolam, vecuronium bromide and potassium chloride each can kill. Here is a look at the drugs as a court considers whether to halt seven executions set for April 17-27:

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MIDAZOLAM

Midazolam is the key drug in Arkansas’ execution protocol and the state’s supply expires April 30. Monday is the first time Arkansas is scheduled to use midazolam in an execution, and the intent is to have it sedate inmates before vecuronium bromide stops their breathing and potassium chloride stops their heart.

“It doesn’t block the experience in the moment,” anesthesiologist Dr. Joel Zivot of Emory University testified in Little Rock federal court this week. “The pain is still there, but they won’t recall it later.”

At normal adult doses of around 4 mg, midazolam can slow or stop breathing to the point that medical literature advises doctors to monitor patients closely. With a 500 mg dose listed in the state’s execution protocol, Arkansas expects that the inmates will not be aware they are dying.

“Midazolam is an appropriate selection,” doctor of pharmacy Daniel Buffington of Tampa, Florida, told U.S. District Judge Kristine Baker.

Doctors testified this week that the drug can “precipitate,” in which a portion of the drug converts to a solid in the bloodstream under certain conditions. Pharmacists who studied botched executions noted the phenomena in a paper published in 2015.

“A rapid precipitation of drug with the injection of a high dose of midazolam (10-500 mg bolus) is a likely scenario,” researchers at the University of Maryland-Eastern Shore wrote in the journal “Research in Social and Administrative Pharmacy.” An author of the paper, Madan Kharel, said this week the document was prepared to caution students about issues they may face as pharmacists, not as a way to instruct them how to conduct executions.

The U.S. Supreme Court in 2015 authorized the use of midazolam in executions, rejecting claims the drug couldn’t adequately sedate inmates.

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VECURONIUM BROMIDE

Vecuronium bromide is a muscle relaxant, but not in the typical sense. Rather than being prescribed for tightness or muscle pain, vecuronium is used to prevent muscles from moving so they don’t interfere with surgeons. After receiving the drug, patients must be on a ventilator or they will suffocate.

“How long can you hold your breath?” Zivot asked in court when asked to describe the drug’s effects. “If given alone, people would be totally aware” that they were becoming oxygen-deprived. He likened it to being held underwater.

The typical dose is up to .1 mg/kg intravenously, or 8.5 mg for the typical inmate set to die this month. Under Arkansas’ protocol, executioners will administer 100 mg, or more than 11 times the typical dose.

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POTASSIUM CHLORIDE

Potassium is essential for maintaining a proper heart rhythm — with levels too high or too low both able to cause cardiac trouble, Zivot said. The anesthesiologist said potassium chloride causes considerable pain when injected and is typically diluted and given over several hours.

He said the drug is typically given in doses of 20 milliequivalents over several hours. Arkansas plans to use 240 mEq immediately after the inmate is injected with vecuronium bromide.

“It’s not only painful, it’s caustic,” Zivot testified. “It will destroy the vein as it passes along its length.”

Kharel, who has Ph.D.s in pharmaceutical sciences and biochemistry, told the AP this week the paralysis caused by the vecuronium bromide should be sufficient to kill the inmates before the executioner delivers a drug to stop the heart.

“The potassium chloride is just to make sure he is dead. It’s a final assurance,” he said.

(© Copyright 2017 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)

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