An H2-receptor antagonist, often shortened to H2-antagonist, is a drug 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.
H2-antagonists are clinically used in the treatment of acid-related gastrointestinal conditions. Specifically, these indications may include: (Rossi, 2004)
H2-antagonists are generally well-tolerated, except for cimetidine where all of the following adverse drug reactions (ADRs) are common. Infrequent ADRs include hypotension. Rare ADRs include: headache, tiredness, dizziness, confusion, diarrhoea, constipation, and rash. (Rossi, 2004)
Examples
Cimetidine was the prototypical member of the H2-antagonists. Further developments, using quantitative structure-activity relationships (QSAR) led to the development of further agents with improved tolerability-profiles.
Prescription medications to treat GERD include drugs called H2 receptor antagonists (H2 blockers) and proton pump inhibitors (PPIs), which help to reduce the stomachacid which tends to worsen symptoms, and work to promote healing, as well as promotility agents which aid in the clearance of acid from the esophagus.
H2 blockers improve the symptoms of heartburn and regurgitation and provide an excellent means of decreasing the flow of stomachacid to aid in the healing process of mild-to-moderate irritation of the esophagus, known as "esophagitis." Symptoms are eliminated in up to 50% of patients with twice a day prescription dosage of the H2 blockers.
H2 blockers are generally less expensive than proton pump inhibitors and can provide an adequate approach as the firstline treatment as well as maintenance agent in GERD for some patients.
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