The Bernese method sounds pretty good to me, but what I don't understand yet is how fentanyl can interfer with it - having a higher affinity than bupe should rather mean that there is no or much less precipitated withdrawal because bupe can't displace the fent.. as the half life of fent passes and it becomes metabolized out, the bupe will take over - this will create kind of a crash but it should be less than either regular precipitated wd (because metabolism is a slow, steady process vs. the almost instant 0 to 100 onset of a new substance after it reaches the receptors) or skipping a dose of fent (because you'll only go gradually down to the partial agonism of bupe instead to zero).
But read before that with some of these fents it is horribly difficult to switch to bupe and I'm glad that I threw my sample of butyr-fent away.. Still wondering if this is the whole thing or whether we have novel derivates with kappa agonism involved which the buprenorphine blocks and thus would out kappa agonists on a sudden turkey. Or these other, lesser known receptors like nociceptin (admittedly, I know less about it yet.)
Some brave individual should try memantine, or other nmda antagonists to help with the transition to bupe. For the usual opiates like morphine they can take much up to almost all symptoms besides diarrhea, for which we have loperamide. If these fents should be too strong for the nmdaa's to work, they might still give you more time to let the body removing these fents and then just titrate the bupe up and when you feel fine again, taper down both. You could use the nmda antag just for the transition or keep it for longer to help with the withdrawal and PAWS like symptoms (anhedonia, fatigue etc).
As bupe is administered subligually, a solution for volumetric dosing would make sense. Maybe go even ower than 0.125mg - if we think of naltrexone, which is used as ultra-low at doses 50 times less the usual starting dose. So maybe even as little as 0.04mg (4mg pill dissolved in 20ml, and use 200ul - just an example, don't have any syringe handy or dropper right now to check the usual amounts of doses), administer sublingually or with a nasal spray (benefit of faster absorption, with the goal to find a dose which is below threshold this doesn't hurt but avoids you quite a bit of waiting time in between the doses). Wait 15min or so, next one. Until you feel some discomfort but still in the range you can live with. Then wait.. after some hours, repeat.
Don't know, how long does usual precipitated withdrawal last? Is this a thing of some hours or even days? Depending on the half life of the previously taken opioid or less/not (so that e.g. fent would be very intense but short lasted, and methadone less extreme but lasting for more than a day).
But as always, not intended to diagnose treat cure or prevent any disease - it's plain theory at the moment.
Good luck anyways
