An<unk> , (H2RA) shortened to H2<unk> , is a classification of drugs used to block the action of histamine on parietal cells in the stomach, decreasing acid production by these cells. These drugs are used in the treatment of dyspepsia; however, their use has waned since the advent of the more effective proton pump inhibitors.
Like the H1-antihistamines, the H2<unk> s are inverse agonists rather than true<unk><unk> s.
H₂-receptor antagonist
Muscarinic antagonist
Muscarinic agonist
Alpha-adrenergic agonist
Beta-adrenergic agonist
Adrenergic agonist
PDE-5 inhibitor
PDE3 inhibitor