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Benzos Benzoz and Anti Histamines

mysafehome01

mysafehome01

Bluelighter
Joined
May 2, 2012
Messages
433
Location
UK
Why is it widely advised to mix Anti Histamines (Promethazine, Diphenydramine) which are both CNS depressants with Opiates. Yet you are STRONGLY dissuaded fro combining Benzos with Opiates.

Both are CNS depressants also both being quite potent. So why is one ok and the other not?
 
I don't know exactly how it works but a lot of antihistamines are also anticholinergics that actually cause stimulation when used in higher doses, so that's why when you take too much of an anticholinergic the physical symptoms are more similar to stimulant OD (high BP, heart rate, faster breathing too I believe) than depressant OD. Mentally you go into delirium. Anti histamine in general seem to only be used as sleep aids in lower doses, so I think it's a mechanism separate from CNS depression that increases the nod/causes sleep but again, I don't know the specifics.
 
I Always combine 50mg Hydroxyzine with 60mg Temazepam. There is nothing bad about the combination. It just makes me feel kind of anesthetized. I manage to stay awake though.
 
I would've guessed that antihistamines have a wider therapeutic range, so you'd need to take a lot of em to get the same synergy causing the increased respiratory depression.
 
kleinerkiffer said:
I would've guessed that antihistamines have a wider therapeutic range, so you'd need to take a lot of em to get the same synergy causing the increased respiratory depression.
Click to expand...

Maybe that is right, the mechanism of action must be different to Benzos. Although both CNS depressants.
 
You should read this http://bja.oxfordjournals.org/content/100/6/747.full
It's really interesting and gives a lot of insight, the mechanism still is not fully understand though.

The last part in particular is really interesting. A network of cortical areas, like the amygdala, has been identified to be responsible for volitional control of breathing and mediating dyspnoea.
Benzos too affect the amygdala
 
Last edited:
I think antihistamines do not but 5-HT2A antagonists do (Hydroxyzine is also a 5-HT2A antagonist).
 
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