From the Guidelines
Cimetidine is a histamine-2 receptor antagonist (H2RA) that decreases the secretion of acid by inhibiting the histamine-2 receptor on the gastric parietal cell, commonly used to treat conditions related to excess stomach acid such as gastroesophageal reflux disease (GERD), peptic ulcers, and heartburn. It is a medication that belongs to the class of drugs called H2 blockers. The typical dosage for cimetidine is 30–40 mg/kg/d, divided in 4 doses, and it is available in syrup formulation for patients aged 16 years and older 1. Cimetidine has been shown to be effective in treating erosive esophagitis in children, but it has some limitations, including the development of tachyphylaxis within 6 weeks of initiation of treatment and a lower effectiveness compared to proton pump inhibitors (PPIs) in symptom relief and healing rates of erosive esophagitis 1. Additionally, cimetidine has been linked to an increased risk of liver disease and gynecomastia, and these associations may be generalizable to other H2RAs 1.
Some key points to consider when using cimetidine include:
- Cimetidine can interact with several medications by affecting liver enzymes that metabolize drugs, potentially increasing blood levels of certain medications like warfarin, phenytoin, and theophylline 1.
- Patients should inform their healthcare provider about all medications they are taking before starting cimetidine.
- Newer H2 blockers like ranitidine and famotidine are often preferred due to fewer drug interactions, but cimetidine remains an effective option for managing acid-related gastrointestinal disorders.
- Cimetidine may be a reasonable alternative to PPIs in patients at lower risk for GI bleeding, and in those who do not require PPI for refractory gastroesophageal reflux disease 1.
From the FDA Drug Label
Cimetidine is a histamine H2-receptor antagonist. Cimetidine competitively inhibits the action of histamine at the histamine H2 receptors of the parietal cells and thus is a histamine H2-receptor antagonist. Cimetidine is a histamine H2-receptor antagonist that works by competitively inhibiting the action of histamine at the histamine H2 receptors of the parietal cells 2.
- It is chemically related to histamine and contains an imidazole ring 2.
- Cimetidine is used to inhibit gastric acid secretion stimulated by food, histamine, pentagastrin, caffeine, and insulin 2.
From the Research
Definition and Properties of Cimetidine
- Cimetidine is a specific competitive histamine H2-receptor antagonist that effectively inhibits gastric acid secretion 3.
- It is an imidazole derivative, belonging to one of the four main structural classes of H2-receptor antagonists 4.
- Cimetidine is used for the treatment of chronic peptic ulceration, hemorrhage from erosive gastritis, and the control of gastric hypersecretion and peptic ulceration in the Zollinger-Ellison syndrome 3.
Comparison with Other H2-Receptor Antagonists
- Cimetidine is less potent than other H2-receptor antagonists such as famotidine, which is approximately 40 times more potent than cimetidine 4, 5.
- Compared to ranitidine, cimetidine has a similar onset of action but a shorter duration of action 5.
- Cimetidine has been shown to be equally effective as other H2-receptor antagonists, such as ranitidine and famotidine, in the symptomatic treatment of intermittent or mild nonerosive gastroesophageal reflux disease (GERD) 6.
Therapeutic Uses and Efficacy
- Cimetidine is effective in promoting the healing of endoscopically diagnosed duodenal ulceration, with a healing rate of over 70% 3, 7.
- It is also used to control gastric acid hypersecretion and peptic ulceration in the Zollinger-Ellison syndrome, with good control of symptoms and no evidence of biochemical or hematologic toxicity 3, 5.
- However, its efficacy in the treatment of gastric ulcer is less clear, and it may not be as effective as other treatments such as proton pump inhibitors for more severe forms of GERD 6.