Obviously it is a CNS depressant and it adds to the sedation of the opioid taken in conjunction with the antihistamine, but I do have two questions that baffle me:
* How does it enhance the euphoria (rather than sedation) induced by the opioid? Is there inherent euphoriant properties of the drug itself? Is this added euphoria due to the anticholinergic properties of the drug? They say that anticholinergics induce a feeling of wellbeing or euphoria and contribute to the antidepressant properties of tricyclic antidepressants - is this the case?
* How does it enhance the analgesia (pain killing) effect of opioids?
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I've never gotten euphoria from anti-cholinergenics. Beside which, non-deliriant anti-histamines also make opioids better for me, I'm a fan of promethazine in particular.
I think that it adds to the 'euphoria' for people by making them nod more, I love nodding; the more of that I get, the better.
As for analgesia, it doesn't add to it. It will only potentiate the CNS depressant effects, and lessen the histamine reaction.
Apparently Hydroxyzine does help pain meds "find" the pain.
I've only gotten euphoria from Antihistamines in conjunction with Diazepam and weed (and ofcourse Opiates ).
Some people can get a small amount of euphoria from certain Antihistamines alone, though it's quite rare.
Apparently they are used clinically to reduce the dose requirement for opioids as they have an 'analgesia-sparing' effect.
^ yeah as a chronic pain patient a lot of the first generation antihistamines have a slight opioid-sparing effect for me especially in IV shots in the ER with morphine... they also reduce the itchiness (pruritis) and nausea and increase the sedation of course.
Those first generation antihistamines (promethazine, diphenhydramine, doxylamine) usually cause euphoria in a small amount of the population and the closely related muscle relaxant orphenadrine epitomizes this effect... from the wiki entry on ethanolamines (that class of antihistamines):
The effects of centrally-acting ethanolamine antihistamines and related drugs can in the case of some drugs create a type of euphoria, a euphoria which is particularly marked with orphenadrine, an antihistamine closely related to diphenhydramine which is used for low back pain, other disorders of skeletal muscle and some aspects of Parkinsonism; the euphoria is significant and reliable enough for orphenadrine to be considered a miscellaneous antidepressant and method for treating adverse effects of opioids.SOURCE
Try to find some stuff on pubmed.com on antihistamines and opiates.
I've read there that Antihistamines increased the amount of the Opiate that would bind to the receptors when they're both taken simultaneously.
There is even a study (which I'm trying to find now!) about Naloxone reversing some effects of some antihistamines...
There's a lot to discover in that field.
They share the same metabolic pathway in the brain
Im moving this to ADD , they will give you a more detailed answer there
Last edited by BingeBoy; 27-11-2008 at 19:38.