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Dope_User
09-11-2004, 19:59
What actually occurs that causes opiates to cause pupil constriction? Ithink there are 2 opioids lacking this side effect, maybe Demerol was one of them. What is different about these other opioids that they don't cause pupil constriction? I know, fairly simple question, but I'm looking for more advanced answers. Thanks.

fastandbulbous
10-11-2004, 05:08
Pethedine (demerol) doesn't produce the pin point pupil effect because the main metabolite, norpethedine, has a pronounced anticholinergic effect, and anticholinergics (eg atropine) produce huge pupils. Norpethedine is also quite good at causing convulsions, which is why there's a limit on how far you can go in using pethedine to support an opiate dependance

BilZ0r
10-11-2004, 08:34
^^^ Really? You learn something new every day.

I'm under the impression Dope_user that we don't know the exact mechanism of opioids effects on pupil size.

CuriousCub
10-11-2004, 13:26
i've seen meperdine, but never Pethedine, as demerol's generic name....what gives?

Dope_User
10-11-2004, 20:37
fastandbulbous, can you provide a source for that info.? Just curious since Blizor said he "that we don't know the exact mechanism of opioids effects on pupil size." I'm especially curious about Demerol and the theory that since it's an opioid is DOES cause constriction but this is reversed by it's "pronounced anticholinergic effect, and anticholinergics (eg atropine) produce huge pupils." Sounds like the opioid causes constricition which is negated by the anticholinergic effect of causing dilation, ultimately leaving a Demerol user with (roughly) normal size pupils, correct?

blase deviant
10-11-2004, 20:58
I've noticed that when taking a 30-45mg dose of DXM in order to consume less opiate, I get about the effects of 1.75-2x or so of the dose of opiate, however I don't get any pupil constriction at all. Normally, at the corresponding opiate dose by effects without DXM (which is 1.75-2x as much), I'd get pinprick pupils, but with DXM they're normal or just about.

Dunno if that helps you guys/gives any clues as to where to look or not...

What I'm curious about is whether benzos/GABA-agonist type drugs enhance or reduce the opiate effects. I've heard users citing studies saying that opiate euphoria/rewarding effects are due to opiate receptors causing dopamine release, while GABA modulates these cells from firing, and therefore should make it less pleasurable, even if it is more sedating. And then I've heard other users swear by it.

It was discussed in full in a 48 post or so thread awhile back about potentiating opiate effects that went into some opiate pharmacology.

Dope_User
10-11-2004, 21:29
blase, benzo's don't potentiate opiates and opiates don't potentiate opiates AFAIK. However, they do, for some people, make the opiate high more enjoyable; while other prefer to just have their opiates only without the extra sedation (and some times confusion, amnesia, blackouts) associated with benzos. It's simply a matter of personal preference. Now back to the original topic please. :)

ebola?
10-11-2004, 22:28
>>I've noticed that when taking a 30-45mg dose of DXM in order to consume less opiate, I get about the effects of 1.75-2x or so of the dose of opiate, however I don't get any pupil constriction at all. Normally, at the corresponding opiate dose by effects without DXM (which is 1.75-2x as much), I'd get pinprick pupils, but with DXM they're normal or just about.
>>

This is unsurprising as DXM dialates the fuck out of my pupils. :)

ebola

astarythe
11-11-2004, 02:05
i wonder if its something that will eventually boil down to pupil dilation is associated with the sympathic CNS, and pinned pupils with the parasympathetic CNS.

fastandbulbous
11-11-2004, 04:53
There's a ref (given below) that states that norpethidine has an inhibitory effect on the vagus nerve supplying the heart. Anticholinergics also have an inhibitory effect on the vagus, but I found a paper on medline that said that they reckoned that norpethidine didn't act via a cholinergic mechanism, so my info might be a bit out of date.

http://www.medsafe.govt.nz/profs/Datasheet/p/Pethidineinj.htm


If you put norphethidine and pharmacology into google it'll list 75 hits, so you can have a look at a few and draw your own conclusions


CuriousCub

the name in the UK is pethidine, but it's demerol in the US (similar to the noradrenaline/norepinephrine naming policy)

Smyth
11-11-2004, 14:10
I know that it due to the parasympathetic part of the nervous system whereas drugs like MDMA affect the sympathetic part. It would probably take a neuroscientist to give you some really meaningful answers on this q.

fastandbulbous
11-11-2004, 15:53
Yes, the vagus nerve is part of the parasympathetic nervous system, it's just that I found a paper on medline that said norpethidine did not exert any effects on cholinergic receptors.

As I said, it was only mentioned in that one paper, but the ref I gave was from a NZ source that looked like it might be from some government source (BilZ0r, any idea? It's your neck of the woods), which stated that norpethidine inhibited the vagus; points towards anticholinergic activity as far as I can see

mitogen
17-11-2004, 03:17
ah,
you mentioned that 35-40mg DXM potentiates opiates effects by ~1.75-2x
you also mentioned that there was a thread a while back about it. (PS, i'm new. is there a bluelight search function i could use to find that?)

i've read up on cold water world about opiate potentiation (promethazine is a good opiate buddy - they use it clinically with intrathecal morphine to kill the itchies. it also seems to potentiate codiene nicely)
cold water world also mentioned DXM as being useful but i've never tried it...

is it really that good?

fastandbulbous
17-11-2004, 04:28
I know they use promethazine to potentiate opiates (it sometimes gets included in a modified version of the Brompton Cocktail recipie), but as well as having antihistamine (H1) actions, it's structurally a phenothiazine, and shares their mind-numbing, chemical lobotomy properties (dopamine antagonist etc), so although it can potentiate opiate analgesia, I very much doubt if you'd be able to say that it was enjoyable.

Don't know much about DXM for the same purpose though, just that as a NMDA antagonist, it can slow the development of tolerance

BilZ0r
17-11-2004, 09:33
DXM is a big CYP2D6 blocker as well... which can be useful for some, but not all (or probably even most) opiates.

When it comes to searching (http://www.bluelight.ru/vb/search.php) there is a link at the top, you can limit it to forum by going to that forum and using the search input located at the bottom right.

CuriousCub
17-11-2004, 11:43
Originally posted by fastandbulbous
There's a ref (given below) that states that norpethidine has an inhibitory effect on the vagus nerve supplying the heart. Anticholinergics also have an inhibitory effect on the vagus, but I found a paper on medline that said that they reckoned that norpethidine didn't act via a cholinergic mechanism, so my info might be a bit out of date.

http://www.medsafe.govt.nz/profs/Datasheet/p/Pethidineinj.htm


If you put norphethidine and pharmacology into google it'll list 75 hits, so you can have a look at a few and draw your own conclusions


CuriousCub

the name in the UK is pethidine, but it's demerol in the US (similar to the noradrenaline/norepinephrine naming policy)

what is this naming policy about? why is it necessary?

fastandbulbous
17-11-2004, 12:49
It's not needed, it just occurs because of some of the differences between US english and UK english (boot/trunk aeroplane/airplane, there's plenty of examples)

blase deviant
17-11-2004, 19:10
Yeah, I find DXM fairly useful, but remember not to use with codeine, and with some drugs (oxy/hydrocodone), it may make it take a bit longer to kick in (in my experience), and with others (dihydrocodeine), it makes it kick in quicker.

Makes it nice to mix hydrocodone and dihydrocodeine, since they kick in pretty close to each other.

Of course, your results may vary. It also reduces itching and nausea, although I sort of like the itching and nausea (call me strange, but the itching and nausea just go hand in hand with the experience, they sorta of... I dunno, of course, I've never thrown up or scratched myself raw, so this might be a blessing for some people).

Smyth
17-11-2004, 19:31
I just re-read the thread posters q and realized what to me is obvious. Demerol also acts at serotonin and to a lesser extent dopamine receptors. I know this because there was a study done to investigate why users of Demerol over the years had reported symptoms indicative of serotonin sydrome. Some highly interesting findings came out these studies that were only published in 1999. Do a search on google for Mark Trudell & chemistry to find the evidence for what I am referring to.