NASHVILLE (AP) — A Tennessee judge on Thursday upheld the state's use of controversial drugs to execute inmates after a challenge by 33 inmates on death row.

Federal public defender Kelley Henry, one of the lawyers representing the inmates, said the plaintiffs will appeal.

In his ruling, Davidson County Chancellor Ellen Hobbs Lyle said the inmates failed to meet two necessary bars, The Tennessean reported. Lyle ruled the lawyers didn't prove that there is a substantially less painful means to carry out the execution or that the drugs the state plans to use would cause the inmate to be tortured to death.

"Although dreadful and grim, it is the law that while surgeries should be pain-free, there is no constitutional requirement for that with executions," Lyle wrote, echoing an argument made by attorneys for the state.

Attorneys for the state and the inmates concluded a nearly two-week trial Tuesday over the new lethal injection procedure.

Tennessee's first execution since 2009 is scheduled for Aug. 9.

The state had used pentobarbital, a barbiturate, but manufacturers have largely stopped selling the drug to anyone using it for executions.

The state adopted a new lethal injection protocol in January that called for a three-drug procedure.

The inmates filed suit in February. They did not argue against the death penalty but focused on the use of midazolam.

Experts who testified on the inmates' behalf said midazolam is often ineffective, leaving people awake and aware of the acidic poison that kills them, using examples from executions across the country.