 | H₂-receptor antagonist: Encyclopedia II - H₂-receptor antagonist - Clinical use of H2-antagonists
H₂-receptor antagonist - Clinical use of H2-antagonists
H₂-receptor antagonist - Indications
H2-antagonists are clinically used in the treatment of acid-related gastrointestinal conditions. Specifically, these indications may include: (Rossi, 2005)
- peptic ulcer disease (PUD)
- gastroesophageal reflux disease (GERD)
- dyspepsia
- stress ulcer prophylaxis (raniditine)
People that suffer from heartburn (GERD) infrequently may take either antacids or H2-receptor antagonists for treatment. H2-antagonists offer several advantages over antacids including longer duration of action (6–10 hours vs 1–2 hours for antacids), greater efficacy, and ability to be used prophylactically before meals to reduce the chance of heartburn occurring. Proton pump inhibitors, however, are the preferred treatment for erosive oesophagitis since they have been shown to promote healing better than H2-antagonists.
H₂-receptor antagonist - Adverse drug reactions
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, 2005) Additionally, cimetidine may also cause gynecomastia in males, loss of libido, and impotence, which are reversible upon discontinuation.
H₂-receptor antagonist - Drug interactions
With regard to pharmacokinetics, cimetidine in particular interferes with some of the body's mechanisms of drug metabolism and elimination through the liver cytochrome P450 pathway. Specifically, cimetidine is an inhibitor of the P450 enzymes CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4. By reducing the metabolism of drugs through these enzymes, cimetidine may increase their serum concentrations to toxic levels. Examples of drugs affected include: warfarin, theophylline, phenytoin, lidocaine, quinidine, propranolol, labetalol, metoprolol, tricyclic antidepressants, some benzodiazepines, dihydropyridine calcium channel blockers, sulfonylureas, metronidazole, and ethanol.
Other related archives1964, 1981, 1988, CYP2D6, CYP2E1, CYP3A4, Cimetidine, ECL cells, GlaxoSmithKline, H1-antihistamines, Proton pump inhibitors, QSAR, Ranitidine, acetylcholine, acid, adverse drug reactions, agranulocytosis, antacids, antagonist, antihistamines, benzodiazepines, calcium channel blockers, cimetidine, competitive antagonist, concentrations, cytochrome P450, diarrhoea, drug, drug metabolism, dyspepsia, ethanol, famotidine, furan, gastrin, gastroesophageal reflux disease, gastrointestinal, guanidine, gynecomastia, headache, histamine, histamine receptor, hypotension, imidazole, impotence, inverse agonists, labetalol, lidocaine, metiamide, metoprolol, metronidazole, nephrotoxicity, nitrogen, nizatidine, omeprazole, pKa, parietal cell, parietal cells, peptic ulcer, pharmacokinetics, phenytoin, propranolol, proton pump inhibitors, quinidine, ranitidine, receptor antagonists, serum, stomach, sulfonylureas, theophylline, thiourea, toxic, tricyclic antidepressants, warfarin
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