At what dose does Quetiapine lose it's affinity for H1 receptor?

[pally pete]

As per the title..

I've looked on various forums, Googled, Reddit etc but had no specific answers. I just read everywhere that in very low doses (25-50/100mg) it acts on the H1 receptor causing most of it's sedative/hypnotic effects.. But when/what dose does it lose this H1 receptor affinity?

Mods please move to relevant section if this is the wrong place or receives no replies (As a lot of my threads seem to

Thanks in advance

 

[sekio]

According to the binding figures on wikipedia, out of all the receptors quetiapine binds to, it actually has the highest affinity to the histamine H1 receptor... I don't think you'll be able to find a dose low enough to not cause H1 blockade.

Fortunately tolerance builds to the sedative effects of H1 antagonists quickly, so repeated daily use will reduce its effectiveness as a sedative.

 

[pally pete]

According to the binding figures on wikipedia, out of all the receptors quetiapine binds to, it actually has the highest affinity to the histamine H1 receptor... I don't think you'll be able to find a dose low enough to not cause H1 blockade.

Fortunately tolerance builds to the sedative effects of H1 antagonists quickly, so repeated daily use will reduce its effectiveness as a sedative.

Thanks for your answer.

I'm now at the prescribed maximum dose of 150 mg Quetiapine. I know some people are on way higher doses, it's just that my shrink thinks 150 mg is the optimum dose for my condition. Sorry to bother you again, but I should have mentioned.. If I want to take breaks from the Quetiapimne maybe 2-3 nights a week but still can't sleep - would a low dose of Mirtazapine help? I'm just concerned that the Quetiapine will be binding to/blocking the H1 receptor rendering the Mirtazapine useless? Also have all the sedating antihistamines at my disposal ()Hydroxyzine, Promethazine, Doxylamine, Diphenhydramine)

Thanks again

 

[sekio]

Mirtazepine would work but of all those, I would recommend doxylamine for sleep the most. I have read many good things about it; namely that it can be more potent than phenobarbital at inducing sleep.

 

[pally pete]

Mirtazepine would work but of all those, I would recommend doxylamine for sleep the most. I have read many good things about it; namely that it can be more potent than phenobarbital at inducing sleep.

That's a surprise. I've read mixed things with regards to Doxylamine. eg it has a high incidence of causing paradoxical effects.. Increased anxiety etc.. Something I don't need but may give a go anyway... The Promethazine & Hydroxyzine massively disappointed me as I was led to believe by my psychiatrists and many others that those were the top 2 sedating antihistamines they would use for anxiety/insomnia. Yet they didn't even touch me at varying doses

Thanks for your time. I'll give Doxylamine a go and see how I respond and report back. Btw, not sure if I mentioned - but I like/want the sedation from the Quetiapine. I just wish it lasted longer, as it usually will only put me out for between 4-6 hours which isn't what I'd hoped for. I was hoping for at least 7-8 hours of sleep from this drug... I also have the choice of Olanzapine, yet what I've read is that Olanzapine has even greater side-effects than Quetiapine.

Something else is that many people suggest that tolerance builds fast to Quetiapine etc... leading to rapid dose escalation and an absolutely brutal withdrawal! Something I don't need after going through countless Benzo and Opiate withdrawals.. Currently tapering my Diazepam jumping from 40 mg - 30 mg on Monday.

Sorry, went a bit off track there..

Cheerz