Pharmaceutical companies have ethically opposed states using their drugs for capital punishment for years, but this is only the second lawsuit to be filed, the AP reported.
McKesson said it wanted nothing to do with executions and accused the state of obtaining vecuronium bromide, a drug used to stop inmates' lungs, under false pretenses.
The state high court in May decided on procedural grounds that the execution could go forward, but did not review the three-drug protocol that death penalty experts have characterized as experimental and risky.
Clark County District Court Judge Elizabeth Gonzalez ordered the delay Wednesday morning in response to a challenge by New Jersey-based drugmaker Alvogen, which says it doesn't want its product, midazolam, used in "botched" executions.
The order is the first time a drug company has successfully sued to halt an execution in the USA involving one of its drugs. But the company did not immediately ask to formally join Alvogen's lawsuit.
Nevada prisons spokeswoman Brooke Santina had no immediate comment.
"The Midazolam has been used in other executions in half a dozen other states with really bad consequences- seriously prolonged executions, with gasping really tortuous effects", says Nancy Hart with Nevada Coalition Against the Death Penalty.
The company points to what it called "botched" executions in other parts of the country where their drug has been used.
The judge ruled that based on that letter, Alvogen had a reasonable probability of winning its lawsuit, and she issued the temporary restraining order against the use of the drug.
Dozier has said repeatedly he wants to die and doesn't care if it's painful.
Assistant Solicitor General Jordan Smith says Nevada never tried to hide its goal. Pharmaceutical companies have resisted the use of their drugs in executions for 10 years, citing both legal and ethical concerns.
The state is planning to use three drugs - midazolam (a sedative), fentanyl (the high-potency opioid) and cisatracurium (a paralytic) - to execute Scott Dozier on Wednesday at 8 p.m. (11 p.m. ET). "In furtherance of this effort, Alvogen does not accept direct orders from prison systems or departments of correction".
Alvogen said that Nevada law is clear that it is an offence to obtain a controlled drug "by misrepresentation, fraud, forgery, deception, subterfuge or alteration". Midazolam will be used in place of the drug Diazepam, which expired. Earlier that year, another inmate, Clayton Lockett, had been injected with midazolam, but instead of becoming unconscious, he twitched, convulsed and spoke.
Pharmaceutical companies have been resisting the use of their drugs in executions for 10 years, citing both legal and ethical concerns, but McKesson Corp. became the first company to sue in the US last year over use of its product in an Arkansas execution, said Robert Dunham, executive director of the Death Penalty Information Center. Fentanyl is used to slow the heart rate, sedate and continue to suppress breathing, and finally Cisatracurium to paralyze the inmate before death. Dozier, who is on death row and is asking a judge to force the state to carry out his execution.
Midazolam has been used with inconsistent results in states including Alabama, Arkansas, Arizona, Florida and Ohio.
"Life in prison isn't a life", the 47-year-old Army veteran and methamphetamine user and dealer told the Las Vegas Review-Journal recently. In court hearings and letters, he said there is a limit to how much artwork and exercise a person can do in prison.
In the November case, Dozier was sentenced to die for robbing, killing and dismembering 22-year-old Jeremiah Miller at the iconic (and now demolished) La Concha motel on the Las Vegas Strip.
Miller's torso was found on April 25, 2002, in a suitcase that had been dumped in a trash bin at the Copper Sands apartment complex in the 8100 block of West Flamingo Road.
He did, however, let federal public defenders review and challenge the execution protocol drawn up a year ago by state medical and prison officials.
Though Dozier dropped attempts to save his own life, he allowed federal public defenders to challenge the execution protocol. They argued the untried three-drug combination would be less humane than putting down a pet.
It's unclear if there's enough opposition to stave off the execution, though the ACLU is looking into the legality of how Nevada obtained the fentanyl. Dunham noted the 2014 executions of Dennis McGuire in OH and Joseph Rudolph Wood III in Arizona left both inmates gasping and snorting before they died.