Indications
H2 receptor blockers, or H2 receptor antagonists (H2RAs), are gastric acid-suppressing agents frequently used in various gastric conditions. The FDA approves these drugs to treat uncomplicated gastroesophageal reflux disease (GERD), gastric or duodenal ulcers, gastric hypersecretion, and mild to infrequent heartburn or indigestion. H2 receptor antagonists may also be used off-label for stress ulcer prophylaxis, esophagitis, gastritis, gastrointestinal bleeding, or urticaria. These drugs are also sometimes included in a multidrug regimen for Helicobacter pylori eradication.[1] Currently, 3 FDA-approved H2RAs are available in the United States, either over-the-counter (OTC) or by prescription. Famotidine and cimetidine are available OTC or by prescription, depending on the dose. Low-dose nizatidine is also available in OTC, but higher doses require a prescription. Ranitidine was previously available but has been withdrawn in the United States and suspended in Europe and Australia for carcinogen contamination during manufacturing.[2][3]
FDA-Approved Indications
H2 receptor antagonists are approved for short-term use in treating uncomplicated gastroesophageal reflux disease (GERD), gastric or duodenal ulcers, gastric hypersecretion, and mild to infrequent heartburn or indigestion. IV famotidine is approved for the short-term treatment of active duodenal and gastric ulcers, maintenance therapy for patients with duodenal ulcers, short-term treatment of gastroesophageal reflux disease, erosive or ulcerative esophagitis due to GERD, and hypersecretory conditions such as Zollinger-Ellison syndrome (ZES).
The American College of Gastroenterology (ACG) guidelines recommend adding bedtime H2RA for patients with persistent nocturnal symptoms while on proton pump inhibitors. In contrast, the ACG recommends proton pump inhibitors (PPIs) over H2 receptor antagonists (H2RAs) for the treatment of erosive esophagitis (EE).[4] ACG also advises the use of high-dose proton pump inhibitor (PPI) therapy, either continuously or intermittently, for 3 days following successful endoscopic hemostatic treatment of a bleeding ulcer.[5]
Off-Label Uses
H2 receptor antagonists can be used off-label for esophagitis, gastritis, gastrointestinal bleeding, urticaria, and stress ulcer prophylaxis.[6] These drugs are also sometimes included in a multidrug regimen for Helicobacter pylori eradication.[1] Although antacids are generally considered first-line agents for heartburn during pregnancy, H2 receptor antagonists may be used if needed.[7] H2RAs have been determined safe for use in children or adolescents with mild or infrequent heartburn symptoms that do not respond to lifestyle changes.[8] The overall therapeutic effectiveness of H2RAs significantly depends on the severity of the gastric disease, dosage regimen, and duration of therapy.
