Kappa Opioid Specific Agonists - Does Maperedine Work?

Mapparadine has been shown to have a therapeutic effect on shivering. But it can't be the only drug out there that has effects on the Kappa opioid receptor. So do other drugs that also affect the Kappa opioid receptors and signal that way also stop shivering? Even if there were 96 randomized clinical trials, there's going to be some other drug in this.