Tolerance to sedation from antihistamines can build very rapidly.
) Also shown affinity towards: (I'm not sure what the action on these is though? Diphenhydramine is a good and cheap option, but you gain a tolerance to it extremely fast, so everyday use is not really beneficial.You can't compare all of these because they all have very different effects around the body.Sure, they may all antagonize H1, but antagonization of H1 is not the only thing that produces sedation!Hydroxyzine - antagonist at the following receptors: α1-adrenergic (Ki = ~300 n M) H1 (Ki = 2 n M) 5-HT2A (Ki = ~50 n M) D2 (Ki = 378 n M) m ACh (Ki = 10,000 n M) Promethazine - antagonist at the following receptors: (*I'll try to find exact numbers) α1-adrenergic (weak to moderate) D2 (weak to moderate) H1 (strong) 5-HT2A (weak to moderate) 5-HT2C (weak to moderate) m ACh (moderate) Doxylamine - I can't find the info on right now, I'll try to find it and add it. Or a couple with different mechanisms to alternate in order to reduce possibility of dependence.Quetiapine - 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 = 5000n M) antagonist Mirtazepine - antagonist at the following receptors: α1-adrenergic (Ki = 608 n M? I have tried diphenhydramine, promethazine, and seroquel.Smart PA: Claims for a combination antihistamine/decongestant agents listed above will usually process at the pharmacy without a PA request if the member has Mass Health medical claims for allergic rhinitis or chronic idiopathic urticaria and a history of paid pharmacy claims for ≥ 14 days out of the last 180 days of loratadine/pseudoephedrine, cetirizine/pseudoephedrine and an intranasal corticosteroid.