Alabama's top prosecutor says an inmate's request for a stay of execution should be denied because he waited too long to complain about the state's execution drug protocol.

Attorney General Luther Strange said in a court filing Friday that Christopher Brooks isn't entitled to a stay of execution because his complaint about drugs could have been brought before midazolam was added to the combination.

Brooks has joined ongoing litigation arguing that midazolam is ineffective as a sedative.

The attorney general's office says Brooks' complaint suggests that any three-drug combination would be unconstitutional, so the switch to midazolam was insignificant and he likely can't prove that a single drug method will work.

He is set to be executed Jan. 21 in the 1993 death of Deann Campbell.