Buprenorphine is often referred to as a 'competitive antagonist' or as a 'partial agonist'. The theory is that it has a high affinity for the opiate receptors but a low efficacy. Itl bind preferentially to 'classic' opioid agonists (high efficacy) like methadone or heroin or oxycodone. The thing is though, unless you take enough buprenorphine to occupy a majority of your opiate receptors, the methadone (or whatever you take) can bind to empty opiate receptors. This will tend to result in an additive effect.
I presume that a sufficiently high dose will compete with any other opioid and thus blockade the subjective (sought for) effects, but it would appear that it requires a high dose. I am of the opinion that the blockade effects are being overstated. I am old enough to remember when we were taught that methadone would blockade other opioids. Again, maybe at huge doses, but everyone prescribed methadone still seems to be able to get high off heroin.
I really do not understand what people get from buprenorphine. All I got was massive anxiety and that was 2mg/day QID. I did take my first huge, white, styrofoam-texture buccal tablet (8 mg) all at once and had to take a Valium. I had a panic attack. Truly awful stuff. Maybe I am in a minority? Maybe it's just me but if the choices were buprenorphine or nothing, I would go with nothing every time. I suspect the anxiety is because buprenorphine is an antagonist at the NOP (ORL1) receptor type. NOP agonists are anxiolytic in action.
I see that thienorphine is being touted as the next step in treating opiate misuse disorder. I have to admire it's design on a technical level. It's a refinement on buprenorphine in every way BUT if people take buprenorphine for fun, I suspect they will find thienorphine MORE fun. Although it's onset is slower, duration has been observed to be three times longer than buprenorphine in animal models. I suspect that with chronic dosing it would only need to be consumed once a week so supervised consumption would be more economically attractive to HR agencies.
Of course, thienorphine analogues that are full agonists are actually less complex in their synthesis. Imagine something that brings a morphine-like high that lasts a week. That could be a problem, especially since Chinese policy is to make specific compounds illegal one by one, not classes.