What are antagonists?

Inhibit action of an agonist with no action in the absence of the agonist (not a reverse agonist) They are classified as receptor antagonists (bind on active site or allosteric site (non-competitive but stops response) of agonist- prevent conformational changes, may be reversible (competitive, shift dose-response curve to right decreasing potency maintaining efficacy) or irreversible (decreases efficacy)) and nonreceptor antagonists (chemical anatagonists (inactivate agonist neutralization), physiologic antagonists reverse effect))