A company that makes a controversial execution drug announced Thursday that it will not sell any of its products to prisons, joining its main competitors in trying to keep their wares out of the death chamber.

Akorn Pharmaceuticals made the move after one of its package inserts was included in court documents filed by Alabama in the appeal of death-row inmate Thomas Arthur.

The Illinois-based drug maker says the material came from its website and was used only as an example, insisting it did not supply the drug in question, a sedative called midazolam, to Alabama's correctional system — either directly or through wholesalers. Going forward, it's taking steps to ensure that none of its drugs are used to kill prisoners.

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"Akorn strongly objects to the use of its products to conduct or support capital punishment through lethal injection or other means," the company said in a statement. "To prevent the use of our products in capital punishment, Akorn will not sell any product directly to any prison or other correctional institution and we will restrict the sale of known components of lethal injection protocols to a select group of wholesalers who agree to use their best efforts to keep these products out of correctional institutions."

The firm follows in the footsteps of other drug companies that make midazolam in stating that it won't allow its products to be used in executions. Groups like Reprieve that oppose capital punishment have pressured the pharmaceutical industry to impose anti-execution restrictions.

Prison systems can still obtain midazolam and other execution drugs from specialty compounding pharmacies — though increasingly they are also shunning the death business.

Midazolam may have a short shelf life as far as executions are concerned. The U.S. Supreme Court agreed to hear a challenge to the drug out of Oklahoma — where a botched lethal injection in April drew national attention to the issue — and will decide whether it's constitutional later this year. Opponents argue that it doesn't anesthetize an inmate against the painful effects of other drugs used in executions.

Alabama has not revealed where it obtained midazolam for the execution of Arthur, who was convicted in a murder-for-hire scheme. His execution has been put on hold until the Supreme Court justices weigh in on the Oklahoma case.

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