The state will use the single-drug lethal injection method instead of the three-drug method it has used in the past, according to Tennessee Department of Correction spokeswoman Dorinda Carter.
"The Department of Correction had been unable to obtain the chemicals necessary to carry out an execution since 2011 due to a widespread shortage" of sodium thiopental, a drug used in the three-drug method, Carter said.
Sodium thiopental puts the prisoner to sleep, with another drug administered to paralyze the prisoner and a third to stop the heart.
In April 2011, Tennessee was among the states that turned over its supplies of sodium thiopental to authorities after concerns arose about how the supply of the drug was imported.
That move came after the company that produced sodium thiopental had bowed to European Union pressure to stop making the drug, creating a shortage. The death penalty has been abolished in all EU nations.
The sodium thiopental shortage forced U.S. states to switch to pentobarbital.
Seven states currently use pentobarbital alone for executions and more are planning to use it, according to Richard Dieter, executive director of the Death Penalty Information Center, a non-profit organization that provides information on capital punishment. Other states use it as part of the three-stage execution process.
Pentobarbital also is commonly used during surgeries and by veterinarians to euthanize animals.
"Given it's used by veterinarians and on humans for other purposes, there's probably a lot out there. But if you have to make a new order, it's hard to get for prisons," Dieter said.
Danish manufacturer Lundbeck and its American subsidiary, Akorn, are controlling the distribution of pentobarbital "and are not allowing its distribution if it is to be used for executions," Dieter said.
Dieter said some states that had been using pentobarbital were having to switch to other drugs or find new sources because of the shortage.
"Everybody that used (sodium thiopental) has switched and now they may have to switch again (from pentobarbital)," Dieter said.