Oh and I doubt that 12-16mg of sub is equivalent to 50-80mg of methadone. Because you can't even transfer from methadone to sub unless you on 30mg or less per day of methadone because the sub won't keep you out of withdrawals. You would have to taper to 30 or less to switch to sub from methadone.
This type of logic does not fully apply in this particular situation, because the reason a methadone patient inducing onto buprenorphine will experience withdrawals is that buprenorphine has a high affinity, yet is only a partial agonist, while methadone has both a high affinity and is a full-agonist.
This causes the unique situation where buprenorphine can induce withdrawal when taken ON TOP of a full agonist opioid, although will suppress withdrawal in the SAME PERSON once the full-agonist has left their body.
You can visualise this by imagining that 100mg of heroin will bind to 50% of the mu-opioid receptors for a couple hours, and activate 100% of those it binds to (causing pleasure), while 50mg of methadone will bind to 75% of the receptors (due to its relatively high affinity) and activate 90% of them, and 12mg buprenorphine will bind to 95% of the receptors, but only activate 50% of them. (These numbers are only an educated guess) (The receptor-activation of a drug is constant regardless of dosage, but the binding is dependant upon dosage and affinity)
Another interesting thing about high-affinity ligands is that they are capable of stripping off a high percentage of a lower-affinity ligand from the receptor. (the calculation for relative numbers of receptors occupied by each ligand looks like this:
[compound_#1_percentage=affinity of compound #1/affinity of compound #2]
[compound_#2_percentage=affinity of compound #2/affinity of compound #1]
Due to this, somebody taking buprenorphine while a large proportion of their receptors are already bound with a more activating opioid will experience subjective dysphoria and withdrawal while the product of the number of receptors bound and the activation DROPS, which is counter-intuitive since you are adding MORE opioids to the body. For the same reason, buprenorphine can be used to revive an overdose (although I would hate to have to convince a jury of this fact in this litigious country).
And antagonists DEactivate all of the receptors they touch, and naloxone and naltrexone both have a VERY high affinity for the receptors so they can strip off any other ligands already bound to the receptor, thus inducing withdrawal.
Additionally, the relative potency of a certain dose of methadone is IMPOSSIBLE to compare with buprenorphine, except on an individual level, due to the wide individual variations in both methadone pharmacokinetics and buprenorphine pharmacokinetics. Buprenorphine is a little more consistant however. Here is a fascinating summary of the factors in methadone dosing:
http://www.atforum.com/SiteRoot/pages/addiction_resources/DosingandSafetyWP.pdf
Another reason this paper is interesting is it explains the concept of "steady state" metabolism very well, which is the reason long-term buprenorphine users (such as myself) are unable to break through the receptor blockade (caused by its high affinity) and get high on other opioids. Other opioids are worthless within 48-72 hours of taking buprenorphine, which is about 36-60 hours after unpleasant withdrawal symptoms begin.
Lastly, many people who find buprenorphine is not working for them as well as they had hoped should try dividing their daily dose into 2, or even 3 equal portions, and possibly lowering their overall dose. I personally take .5mg of buprenorphine twice a day most days, and sometimes I take .5mg 3X a day. Many people who have insomnia or headaches or somnolence from buprenorphine may find that this is due to taking too much. Buprenorphine DOES prevent you from attaining proper sleep structure, especially when the body has more than it can handle, which can lead to being tired during the day. Everybody should personally experiment with lowering their dose to the lowest amount that they feel comfortable with, because there are honestly NO benefits of taking any more than that. If you are being prescribed 24mg/day and only taking 4mg a day, just think of the amazing stockpile you can attain, and the medical bills you can avoid. Of course if you do not have the willpower to do this safely, you should tell your doc everytime you wish to lower your dose.
