Hi all,

I was asking the same question numerous times in the boards, then I realized I had the answers I needed on my bookshelf (silly me!) in one of my favorite books. Guess I was too hazy to remember. I spent last night catching up on my reading. I'm sharing it with you.

All excerpts to follow are from 'A Primer of Drug Action' by Robert M. Julien, M.D., Ph.D. It is unbiased and incredibly informative. Anything in parenthesis are my comments, not his.

Here we go:

Buprenorphine has a half life of 37 hours. (this we know...but please indulge further explanation.) Half-life is based on 6 half-lives(!).

This means that in 37 hours, 50% of the original dosage will remain in the body. In another 37 hours, 25% will remain; another 37 hours, 12.5% remains; another 37, 6.2% remains; 37 more, 3.1% remains; and finally the last 37 hours, 1.6% remains. (Wow!)

Sublingual naloxone has a half life of 1.1 hours. (So, the naloxone is negligible by comparison. It is eliminated FAR more quickly than the buprenorphine in Suboxone.) Sublingual naloxone is poorly absorbed.

(Next):

We've all heard of the partial agonist (which means 'activates'), pure antagonists (which means 'inhibits'), mixed agonist-antagonist (yuck), and (our favorites) the full agonist (morphine, H, those pills we love, etc.).

Naloxone is a pure antagonist which means it blocks the access of other opioids. (To be a bit more technical), it blocks access of both endogenous ligands (here, endorphins), or an exogenous drug (e.g., any morphine derivative -- other opioids) either present in the body -- precipitating withdrawal -- OR ADMINISTERED WITH OR AFTER THE ANTAGONIST -- RESULTING IN NO EFFECT OF THE AGONIST. (**That's what I wanted to know.**)

A partial agonist (bupe) binds to the opioid receptors but has a low intrinsic activity (low efficacy). It therefore exerts an analgesic effect, but such an effect has a ceiling at less than the maximal effect produced by a pure agonist opioid. Buprenorphine is the prototype partial agonist opioid. When administered to a "naive" individual, analgesia is observed; when administered to an addict, however, a blockade of the pure agonist can occur and withdrawal can be precipitated. Compared to a mixed agonist-antagonist, the partial agonist buprenorphine binds to all three types of opioid receptors, albeit with lower efficacy.

Buprenorphine is a newer, semisynthetic, partial agonist (at the risk of being redundant) opioid whose action is characterized by limited stimulation of mu receptors, which is responsible for its analgesic properties. As a partial agonist, however, there is a ceiling to its analgesic effectiveness, as well as to its potential for inducing euphoria (don't I know it!) and respiratory depression.

Bupe has a very long duration of action (24 hours) because it binds very strongly to mu receptors, limiting its reversibility by naloxone when reversal is considered necessary. (Naloxone can stop an overdose of opiates if caught in time.)

The drug can be given by oral, parenteral, or sublingual routes. At LOW doses, buprenorphine can substitute for morphine (in morphine-dependent individuals -- this means you --- H turns to morphine in the body) and it is analgesic (in nontolerant individuals). However, higher doses do NOT substitute well for morphine, and they can precipitate withdrawal symptoms. (So, I guess, for us, less IS more!)

(CAPS in the above writing were added by me.) Sorry for any redundant material, but I was picking and choosing from various parts of the book.

I highly recommend the above referenced book if you want a better understanding of how drugs work. Get the most recent edition.

A simpler, great book, also (another fave of mine) is called, "Buzzed: Just say Know" by Cynthia Kuhn, Scott Swartzwelder, and Wilkie Wilson, of the Duke Univ. Medical Center. It's the truth, not government propaganda and bull****.

Hope you got this far...[].