[JamesBarney]

I don't think it has the same binding affinity as more powerful opiods which reduces it's addictive potential, as well the risk of overdose.

[__blockcipher__]

It activates mu-opioid quite strongly but not the other receptors as much (I forget their names).

Interestingly, it has a mix of opioid antagonists and agonists. I’m not sure if that specifically is why tolerance doesn’t build aggressively, or if it’s some other MoA like nmda receptor antagonism