(Reuters) - Texas, which executes more people than any other U.S. state, said on Tuesday it will switch to using a single drug in carrying out the death penalty after it exhausted the usable supply of another drug.

Texas had been using a three-drug cocktail to carry out executions but will now switch to using only pentobarbital, a sedative sometimes also used to euthanize animals.

"We will be using a lethal dose of pentobarbital," Jason Clark, spokesman for the Texas Department of Criminal Justice, said in an email.

The state was forced to switch after its available supply of a second drug in the cocktail, pancuronium bromide, expired and was no longer usable. The next execution in Texas is scheduled for July 18.

(Reporting and writing By Greg McCune; Editing by Cynthia Johnston)