RALEIGH (AP) — The state of North Carolina has changed the protocol for executing death row inmates by using one lethal chemical instead of three drugs.

Department of Public Safety Secretary Frank Perry signed updated rules two weeks ago that describe how to carry out an execution.

The new rules say prison officials will inject a short-acting barbiturate such as pentobarbital. Previous rules directed a three-drug method, but many states with capital punishment have moved away from that approach.

The change is important because lawyers for some North Carolina prisoners argue the three-drug method is cruel and unusual punishment. The Court of Appeals delayed arguments previously set for Wednesday in a lawsuit while state and prisoner attorneys examine the rules.

The liberal-leaning group NC Policy Watch first reported on the new rules.