Hah Neighborhood Threat or Cane2the left are the ones to talk to about buprenorphone really..
People's opinions differ on buprenorphine a lot.. some love it, some hate it, some take high doses, some take low doses - but the idea behind taking a smaller dose is all about buprenorphine only being a
partial opioid agonist.
The term "agonist" refers to the drug binding to the opioid receptor in the brain and causing all the lovely opiate effects. An opioid agonist causes opiate effects.* A dopamine agonist binds to dopamine receptors, and causes a different set of effects, serotonin agonists bind to serotonin receptors and cause another set of effects etc..
As buprenorphine is only a partial opioid agonist, it doesn't have the full-on effects that a full opiate agonist would. This is why a lot of people find it doesn't feel the same as other opiates, and isn't as recreational.
However, after you take the buprenorphine, some of it is metabolised into norbuprenorphine. This is a full agonist - so feels much more like other opiates than buprenorphine does.
Buprenophine has a
higher receptor affinity than norbuprenorphine - this means that it binds more tightly to the receptors than norbuprenorphone does, so the norbuprenorphine doesn't get a look in and you only feel the buprenorphine effects. However, at lower doses, there is less buprenorphine around so norbuprenorphine does have an effect. This means you have a full opioid agonist having an effect as well as just a partial one, so overall a smaller dose of bupe can feel more like a proper opiate than a large one (to some people, me included).
Haha did that make sense? Have a look at the
buprenorphine megathread for more info on bupe.
Sorry if that was all a bit confusing, am quite sleep deprived!
Essentially, smaller doses means the metabolite norbuprenorphine has an effect too, and norbuprenorphine produces more opiate-like effects than buprenorphine.
*technically, "opiate" refers to a drug derived from the opium poppy plant - many drugs referred to as opiates are actually synthetic and not derived from opium poppies at all, and are more currectly called opioids. An opioid is defined as any substance that binds to opioid receptors in the brain - but often the terms are used interchangably and I wouldn't worry about them too much