The drug used in Tennessee’s failed execution has come under past scrutiny

The lethal drug administered in Tennessee’s failed attempt to execute Christa Pike has been used in multiple states that carry out the death penalty and by the U.S. government after President Donald Trump resumed federal executions during his first term.

Pike, 50, remained alive after two doses of pentobarbital were administered Wednesday, according to her attorneys and media witnesses. One of her lawyers said Thursday that she was being treated at a hospital.

Tennessee officials haven’t explained yet what went wrong during the execution.

Republican Gov. Bill Lee ordered a third-party review to determine what happened and said another scheduled execution in Tennessee will not take place this year.

What is pentobarbital?

Pentobarbital is a barbiturate, a class of drugs that depresses the central nervous system.

Approved medical uses include sedation, short-term treatment of insomnia, preparation for anesthesia and emergency control of certain severe seizures. It is also used in veterinary euthanasia.

In an overdose, it can produce coma, suppress breathing and cause circulatory collapse and death.

Why is it used in executions?

For years, lethal injections commonly used three drugs: an anesthetic, a paralytic that stopped breathing and potassium chloride to stop the heart.

That method drew criticism because if the anesthetic failed, the paralytic could prevent a prisoner from communicating pain. It also became difficult to maintain after drugmakers restricted distribution for executions.

The pentobarbital protocol was adopted at the federal level during Trump’s first term to replace a three-drug mix used in the 2000s.

As with Tennessee’s guidelines, the federal death penalty protocol calls for administering a 5-gram dose of pentobarbital; in medical settings, patients typically receive a fraction of a gram.

Trump resumed the federal death penalty after an informal moratorium during previous administrations. The federal government used pentobarbital in 13 executions between 2020 and 2021, contributing to making Trump the most prolific execution president in over 130 years.

During the Biden administration, the Justice Department stopped executions with pentobarbital after a government review raised concerns about the potential for “unnecessary pain and suffering.”

After Trump came back to power, the Justice Department in 2026 reauthorized the use of lethal injections with pentobarbital.

How do guidelines vary in different states?

Georgia and Texas use a similar protocol to Tennessee, administering a second dose only if the first is unsuccessful. South Carolina, which turned to pentobarbital in 2024, automatically gives inmates two 5-gram doses spaced about 10 minutes apart.

Lawyers for people on death row have argued that giving such a large dose twice was proof the condemned were dying a lingering death, still conscious and feeling like they were drowning when fluid rushed into their lungs.

But a South Carolina Department of Corrections attorney said inmates are unconscious in well under a minute and can’t feel anything. The heart may show an occasional flicker on a monitor, but that’s because it is the last organ to use the body’s stored oxygen and has residual electrical impulses.

When past lethal injection executions have gone wrong, it is usually because an IV line can’t be properly inserted and the execution is stopped before the drugs are given. There have also been cases of violent reactions or prolonged time passing before death when a new combination of drugs is used.

Witnesses to pentobarbital executions frequently report that inmates stop breathing and become still less than a minute after getting the drug.

What have experts said about the drug?

Experts quoted in the 2025 federal review argue pentobarbital can cause pulmonary edema, a buildup of fluid in the lungs that may create a sensation of suffocating.

The review concluded that “there remains significant uncertainty about whether the use of pentobarbital as a single drug lethal injection causes unnecessary pain and suffering” and advised that the government should “err on the side of humane treatment.”

Other specialists quoted in a report released by the second Trump administration said a lethal dose causes unconsciousness before that occurs.