is important to know that not all drugs exert effects by 
interacting with a receptor. Antacids,for instance, chemically neutralize excess gastric acid, thereby reducing stomach upset. 
• Although the majority of drugs work through interaction with specialized biological molecules called receptors, there are few 
groups of drugs that do not relay on receptors to mediate their effect for example, medication that depend on physical 
properties (osmosis, adsorption, radioactivity), chemical properties (antacids, chelating agents).