List of sedating antihistamines
One study on diphenhydramine for example found sedation to be equal to placebo after just 4 days of daily use. I think dopamine blockade increases melatonin production or something?Binding affinity chart for diphenhydramine: I wish I could find graphs like this for each drug, that would be a lot easier to compare. I do have the binding affinities for the other drugs you mentioned, but I will have to post them later as I have to get off the internet for a while. Hydrazine is a toxic chemical or an old group of MAOIs which are rarely ever used anymore due to toxicity. I'm not psyched about the propensity for both antihistamine and antidopamine actions to cause/exacerbate RLS and other movement disorders though.Anyway I'd like to know which of them (regardless as their branding as 'antihistamines') has the strongest affiliations with these receptors known for producing hypnotic properties.
Diphenhydramine has potent antagonization effects on Histamine H1 receptors, and Muscarinic acetylcholine receptors (all subtypes).
I know this thread is a little old, but I thought I'd chime in anyways.
You can't compare all of these because they all have very different effects around the body.
*Note: some of the ones listed as antagonists might possibly be inverse agonists. I have tried diphenhydramine, promethazine, and seroquel.
Hydroxyzine - antagonist at the following receptors: α1-adrenergic (IC50 = 94n M) α2-adrenergic (IC50 = 271n M) D1 (IC50 = 1268n M) D2 (IC50 = 329n M) D3 (unspecified) D4 (unspecified) H1 (IC50 = 30n M) 5-HT1A (IC50 = 717n M) 5-HT2A (IC50 = 148n M) 5-HT2C (unspecified) 5-HT7 (unspecified) m ACh receptor (IC50 = α1-adrenergic (Ki = 608 n M? Out of those, seroquel was by far the most sedating, with promethazine coming in second.