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.

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.

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.

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.

The move was part of Trump’s efforts to resume 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.

States maintain their own procedures.

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.