A<unk>  acts to inhibit the action at<unk>  receptors.
Many of the most important medications of this class selectively act at the 5-HT3 receptor, and thus are known as 5-HT3<unk> s. However, other drugs such as ketanserin act upon other types of<unk>  receptors.
Serotonin antagonist
Dopamine agonist
Nicotinic antagonist
Dopamine antagonist
Muscarinic antagonist
Adrenergic agonist
Alpha-adrenergic agonist
Muscarinic agonist