Why does atropine act on histamine receptors?
This has to do with a concept in pharmacology known as selectivity and specificity. All drugs act at multiple sites, but usually act more potently at one rather than all others. This is selectivity. Specificity would mean the drug acts at only ONE site, and this is hardly ever observed. The idea is that atropine might act on histamine receptors, as well as some others, but at much higher concentrations than required to block muscarinic cholinergic receptors.
