Dose response curves of a full agonist, partial agonist, neutral antagonist, and<unk>  In pharmacology, an<unk>  is a drug that binds to the same receptor as an agonist but induces a pharmacological response opposite to that of the agonist. A neutral antagonist has no activity in the absence of an agonist or<unk>  but can block the activity of either.<unk> s have opposite actions to those of agonists but the effects of both of these can be blocked by antagonists. A prerequisite for an<unk>  response is that the receptor must have a constitutive (also known as intrinsic or basal) level of activity in the absence of any ligand. An agonist increases the activity of a receptor above its basal level, whereas an<unk>  decreases the activity below the basal level. The efficacy of a full agonist is by definition 100%, a neutral antagonist has 0% efficacy, and an<unk>  has < 0% (i.e., negative) efficacy.
Inverse agonist
Muscarinic antagonist
Dopamine agonist
Enzyme potentiated desensitization
P-i mechanism
Alpha-adrenergic agonist
Dopamine antagonist
Opioid antagonist