Opioids Opiate tolerance and respiratory depression

[Dobe]

Is an individual with opiate tolerance also tolerant to the unwanted side effect of respiratory depression? Googling for info produces mixed results... what's the truth?

If people with high tolerance are resistant to respiratory depression then how is it possible for heroin addicts to OD?

 

[tricomb]

I've been told by an overlwhelming amount of doctors, not just doctors but specialists, anesthesiologists, and addicts, alike, and they both conclude that no, you never develop *enough* tolerance to the CNS depressant action.


Refer to a basic dose-response curve for morphine IV and multiple dose PO to see for yourself. Technically, the analgesic potential of full agonist opioids are virtually unlimited based on user tolerance of side effect as you near the extreme end of the spectrum. (I once met a lady rx'd 3500 milligrams of morphine every 8 hours) So yeah, until you can't breathe on your own anymore, opiate tolerance has proven time and time again that I would say it's never possible to fully develop a tolerance for the CNS respiratory depressant effect, the drugs can be used in high doses to euthanize animals and humans alike. So think about that for logic.

 

[OntarioGuy]

^ I once lived with a lady who was Rx'd 400 mg's of methadone per day (in one dose) and she got a huge, I mean HUGE, bottle of Xanax every month, like 16 mg's a day, plus a cocktail of other benzos....

That would make me stop breathing for sure,and I'm sure alot of other people as well...Maybe some people just have a natural tolerance to the respiratory effects.

 

[bunge]

^
Personally I doubt that anyone can have much of a natural tolerance to just the respiratory effects. Some people can have a lower sensitivity to certain substances either through differences in liver chemistry or brain chemistry (or both.lol).
The side effects of any drug will diminish with time and tolerance and this does happen with the bad ones like respiratory depression but tends happen with the good ones (euphoria) first. Hence why people manage to OD, in chasing the euphoria they increase the dose past their tolerance to the euphoria effect but then go too far past their tolerance of the unwanted effects.
Hope that made some sense. I didnt sleep well last night and tend to ramble when im tired.lol

 

[Dobe]

I think this is one of the better web sources on the subject:

http://www.ncbi.nlm.nih.gov/pubmed/10707430

"The degree of tolerance also determines risk. Tolerance to respiratory depression is less than complete, and may be slower than tolerance to euphoric and other effects. One consequence of this may be a relatively high risk of overdose among experienced opioid users."

 

[Dobe]

I think this is relevant too.

http://www.bluelight.ru/vb/threads/663846-H-I-don-t-get-it?p=11294835&viewfull=1#post11294835

Cross tolerance to euphoria can be higher than cross tolerance to respiratory depression as well, I've noticed when switching to a new opioid, especially switching to morphine or heroin from a synthetic opioid, I noticed far more respiratory depression at doses that were equivalent for euphoria or analgesia. So experiencing more noticeable respiratory depression from heroin than oxy may be "normal" but that doesn't make it safe. There is a small margin or error between high and dead with heroin, that window is more narrow than with some other opioids.

 

[Mr.Scagnattie]

I think this is one of the better web sources on the subject:

http://www.ncbi.nlm.nih.gov/pubmed/10707430

"The degree of tolerance also determines risk. Tolerance to respiratory depression is less than complete, and may be slower than tolerance to euphoric and other effects. One consequence of this may be a relatively high risk of overdose among experienced opioid users."

Interesting. I always assumed that the correlation between drug effect tolerance and respiratory depression was 1:1. But, in a way, it does make sense that it wouldn't be that in all cases, and on an individual basis, perhaps much further from a 1:1 ratio, which is quite a scary thought because you don't know where you fall until something bad happens.

 

[tricomb]

Maybe some people just have a natural tolerance to the respiratory effects.

I don't think this is possible.

 

[OntarioGuy]

Or build a higher tolerance to the effects with repeated faster use then the average person.

 

[Swimmingdancer]

Is an individual with opiate tolerance also tolerant to the unwanted side effect of respiratory depression? Googling for info produces mixed results... what's the truth?

If people with high tolerance are resistant to respiratory depression then how is it possible for heroin addicts to OD?

People are not resistant to respiratory depression. Even if someone has a high tolerance there is still a higher dose which could kill them, I really don't think anyone ever has such a high tolerance that there is no dose that would cause them dangerous respiratory depression (and you can die in other ways too). Being "tolerant" to opioids doesn't mean the person has become immune to their effects. It just means they have developed a substantial amount of tolerance to the desired effect so they would require a higher dose to achieve it than a person without tolerance. Tolerance to different aspects of opioid effects such as euphoria, pain relief, pupil constriction and respiratory depression happens at different rates (as I alluded to in my post from another thread that you quoted above). I have read a few studies on that.

Some ways in which experienced heroin users OD are:
- street heroin is never pure so potency can vary a lot from source to source/batch to batch (even from the same supplier) and so people will do their usual amount, only to find out it's much stronger
- people are chasing the high and trying to get as high as possible, and as I said there is a fine line between high and dead
- people assume that if they don't feel very high that they aren't at risk of an OD from increasing their dose
- people will use other CNS-depressant drugs, such as benzos, close to the same time (a cause of lots of ODs)
- tolerance is complex and not static, it can be affected by lots of things, even your location (a lot of ODs happen when in an unfamiliar place because tolerance is reduced)