Texas is changing one of the drugs used to conduct executions in the nation's busiest death penalty state due to a shortage of a sedative it's used for nearly three decades, officials said Wednesday.

Texas Department of Criminal Justice officials said they plan to substitute pentobarbital for sodium thiopental in the three-drug cocktail used for lethal injections. Pentobarbital, a surgical sedative, also is commonly used to euthanize animals and recently has been used for executions in Oklahoma.

A shortage of sodium thiopental has forced multiple states to scramble for substitutes. Texas has used the drug since becoming the first state to do lethal injections in 1982. Texas' supply of sodium thiopental expires at the end of this month and an execution is set for early April.

Agency spokeswoman Michelle Lyons said Rick Thaler, director of the agency's institutional division, authorized the switch.

"It's in the state statute that changes in chemical and dosages may be made at the discretion of the institutional division director," she said. "We were looking for a drug with similar properties to sodium thiopental and this drug has been used in the Oklahoma execution process so there is a precedent for its use in executions."

Pentobarbital use has survived court challenges in Oklahoma, which also uses it in conjunction with two other drugs that paralyze inmates and stop their hearts. Ohio recently switched to pentobarbital as the sole drug used for its executions.

Texas used the electric chair for executions from the 1920s until the 1960s.

Texas inmate Charlie Brooks became the first in the nation to be executed by injection on Dec. 7, 1982.

Texas has since executed 466 people, far more than any other state. Seventeen inmates were put to death last year in Texas and two have been executed this year.

Convicted killer Cleve Foster, who is scheduled for execution on April 5, would be the first to be given the new drug in Texas. At least four other inmates are on the state's execution schedule for the coming months. Other drugs used in the process are pancuronium bromide and potassium chloride.

The sodium thiopental shortage has delayed executions in several states and an Associated Press review found that at least five states _ Arizona, Arkansas, California, Georgia and Tennessee _ had to turn to England for their supply of the drug.

Nebraska, meanwhile, secured a stockpile from an Indian firm. On Tuesday, Drug Enforcement Administration agents seized Georgia's supply of the sedative, saying officials had questions about how the drug was imported.