Famotidine is a propanimidamide and histamine H2-receptor antagonist with antacid activity. As a competitive inhibitor of histamine H2-receptors located on the basolateral membrane of the parietal cell, famotidine reduces basal and nocturnal gastric acid secretion, resulting in a reduction in gastric volume, acidity, and amount of gastric acid released in response to various stimuli.
Information about Famotidine
Famotidine is a histamine type 2 receptor antagonist (H2 blocker) which is commonly used for treatment of acid-peptic disease and heartburn.
Liver safety of Famotidine
Famotidine has been linked to rare instances of clinically apparent acute liver injury.
Mechanism of action of Famotidine
Famotidine (fam oh' ti deen) was the third H2 blocker introduced into clinical practice in the United States and is a commonly used agent for treatment of duodenal and gastric ulcer and gastroesophageal reflux disease. The H2 blockers are specific antagonists of the histamine type 2 receptor, which is found on the basolateral (antiluminal) membrane of gastric parietal cells. The binding of famotidine to the H2 receptor results in inhibition of acid production and secretion, and improvement in symptoms and signs of acid-peptic disease. The H2 blockers inhibit an early, “upstream” step in gastric acid production and are less potent that the proton pump inhibitors, which inhibit the final common step in acid secretion. Nevertheless, the H2 blockers inhibit 24 hour gastric acid production by about 70% and are most effective in blocking basal and nocturnal acid production.
FDA approval information for Famotidine
Famotidine was first approved for use in the United States in 1986 and more than 3 million prescriptions for it are filled yearly. Famotidine is now available both by prescription and over-the-counter. The listed indications for famotidine are duodenal and gastric ulcer disease, gastroesophageal reflux and prevention of stress ulcers.
Dosage and administration for Famotidine
Famotidine is available in tablets of 20 and 40 mg in several generic forms and in parenteral forms under the brand name Pepcid. Over-the-counter formulations are typically gelcaps or tablets of 10 or 20 mg. Liquid solutions are also available for intravenous use. The typical recommended dose for therapy of peptic ulcer disease in adults is 40 mg once daily for 4 to 8 weeks and maintenance therapy of 20 mg daily. Lower, chronic and intermittent doses of famotidine are used for therapy of heartburn and indigestion.
Side effects of Famotidine
Side effects are uncommon, usually minor, and include diarrhea, constipation, fatigue, drowsiness, headache and muscle aches. Famotidine is metabolized by the hepatic cytochrome P450 system, but has minimal inhibitory effects on the metabolism of other drugs, making it less likely to cause drug-drug interactions than cimetidine.
The antiulcer agents in clinical use