Opioids primarily work by binding to and activating inhibitory opioid receptors in the periphery, spinal cord, and brain.

“By and large, they all have the same or similar mechanisms of actions, working on opioid receptors. This is getting back to your original question to me about where these things work. There are opioid receptors in the periphery. There are rich sources of opioid receptors in the spinal cord and the dorsal-- the back part of the spinal cord. And then there are many areas in the brain that are rich in opioid receptors. It's all a naturally occurring area. And when we put in an opioid by mouth, we're binding to those receptors and activating those neural circuits. In many cases when I say activating, they have an inhibitory role.”