Description

Simple

A medication used to treat ulcers, acid reflux, and conditions where the stomach produces too much acid.

Clinical

A histamine H2 receptor antagonist used to treat duodenal ulcers, benign gastric ulcers, GERD, and Zollinger-Ellison syndrome.

Overview

Famotidine is a competitive histamine-2 (H2) receptor antagonist that works to inhibit gastric acid secretion. It is commonly used in gastrointestinal conditions related to acid secretion, such as gastric ulcers and gastroesophageal reflux disease (GERD), in adults and children.[8] Compared to other H2 receptor antagonists, famotidine displays high selectivity towards this receptor; in a study consisting of healthy volunteers and patients with acid hypersecretory disease, famotidine was about 20 to 50 times more potent at inhibiting gastric acid secretion than [cimetidine] and eight times more potent than [ranitidine] on a weight basis.[2] Famotidine is used in various over-the-counter and off-label uses.[8] While oral formulations of famotidine are more commonly used, the intravenous solution of the drug is available for use in hospital settings.[Read more

Pharmacology

Indication

Famotidine is indicated in pediatric and adult patients (with the bodyweight of 40 kg and above) for the management of active duodenal ulcer (DU), active gastric ulcer, symptomatic non-erosive gastroesophageal reflux disease (GERD), and erosive esophagitis due to GERD, diagnosed by biopsy.[ Read more

Pharmacodynamic

Famotidine decreases the production of gastric acid, suppresses acid concentration and pepsin content, and decreases the volume of gastric secretion. Famotidine inhibits both basal and nocturnal gastric acid secretion, as well as acid secretion stimulated by food, caffeine, insulin, and pentagastrin... Read more

Mechanism of action

Histamine acts as a local hormone that stimulates the acid output by parietal cells via a paracrine mechanism. Neuroendocrine cells called enterochromaffin-like (ECL) cells lie close to the parietal cells and regulate the basal secretion of histamine. Histamine release is also promoted from stimulat... Read more

Absorption

Following oral administration, the absorption of famotidine is dose-dependent and incomplete.[3... Read more

Protein binding

The protein binding of famotidine is about 15 to 22%.[3]

Volume of distribution

The steady-state volume of distribution ranges from 1.0 to 1.3 L/kg.[3] Famotidine is found... Read more

Clearance

Renal clearance is 250-450 mL/min, indicating some tubular excretion. Because the renal clearance rate exceeds the glomerular filtration rate, famotidine is thought to be mainly eliminated via both glomerular filtration and renal tubular secretion.[ Read more

Half life

The elimination half-life is about 2 to 4 hours.[3] The half-life is expected to increase n... Read more

Route of elimination

About 65-70% of the total administered dose of famotidine undergoes renal elimination, and 30-35% of the dose is cleared by metabolism.[5] Following intravenous adminis... Read more

Toxicity

The oral LD50 is 4049 mg/kg in rats and 4686 mg/kg in mice. The subcutaneous LD50 is 800 mg/kg in rats and mice. The lowest published toxic dose (TDLo) in man following oral administration is 4 mg/kg/7D.[ Read more

Adverse Effects

Contraindications

  • Route:
    • Intravenous
    • Oral
  • Hypersensitivity:
    • H2-receptor antagonists
  • Regions: US

Food Interactions

  • Avoid alcohol.
  • Limit caffeine intake.
  • Take with or without food. Food slightly increases bioavailability, but not to a clinically significant extent.

Interactions

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  • Paracetamol(acetaminophen)
  • Paxil(paroxetine)
  • Pamelor(nortriptyline)
  • Panadol(acetaminophen)
  • Patanol(olopatadine ophthalmic)
  • Pataday(olopatadine ophthalmic)
  • Parnate(tranylcypromine)
  • Pazeo(olopatadine ophthalmic)
(R)-warfarin
The metabolism of (R)-warfarin can be decreased when combined with Famotidine.
2,5-Dimethoxy-4-ethylamphetamine
2,5-Dimethoxy-4-ethylamphetamine may decrease the sedative and stimulatory activities of Famotidine.
2,5-Dimethoxy-4-ethylthioamphetamine
2,5-Dimethoxy-4-ethylthioamphetamine may decrease the sedative and stimulatory activities of Famotidine.
4-Bromo-2,5-dimethoxyamphetamine
4-Bromo-2,5-dimethoxyamphetamine may decrease the sedative and stimulatory activities of Famotidine.
6-O-benzylguanine
The metabolism of 6-O-benzylguanine can be decreased when combined with Famotidine.
8-azaguanine
The metabolism of 8-azaguanine can be decreased when combined with Famotidine.
8-chlorotheophylline
The metabolism of 8-chlorotheophylline can be decreased when combined with Famotidine.
9-Deazaguanine
The metabolism of 9-Deazaguanine can be decreased when combined with Famotidine.
9-Methylguanine
The metabolism of 9-Methylguanine can be decreased when combined with Famotidine.
Abafungin
Famotidine can cause a decrease in the absorption of Abafungin resulting in a reduced serum concentration and potentially a decrease in efficacy.
Abexinostat
The risk or severity of QTc prolongation can be increased when Famotidine is combined with Abexinostat.
Acebutolol
The risk or severity of QTc prolongation can be increased when Famotidine is combined with Acebutolol.
Acefylline
The metabolism of Acefylline can be decreased when combined with Famotidine.
Acenocoumarol
The metabolism of Acenocoumarol can be decreased when combined with Famotidine.
Aceprometazine
The risk or severity of QTc prolongation can be increased when Famotidine is combined with Aceprometazine.
Acetaminophen
The metabolism of Acetaminophen can be decreased when combined with Famotidine.
Acetyldigoxin
The risk or severity of QTc prolongation can be increased when Famotidine is combined with Acetyldigoxin.
Acetylsalicylic acid
The excretion of Famotidine can be decreased when combined with Acetylsalicylic acid.
Acrivastine
The risk or severity of QTc prolongation can be increased when Famotidine is combined with Acrivastine.
Acyclovir
The excretion of Famotidine can be decreased when combined with Acyclovir.
9 References
  1. 1 . Chremos AN: Clinical pharmacology of famotidine: a summary. J Clin Gastroenterol. 1987;9 Suppl 2:7-12. doi: 10.1097/00004836-198707002-00003.PubMed: 2887616
  2. 2 . Langtry HD, Grant SM, Goa KL: Famotidine. An updated review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in peptic ulcer disease and other allied diseases. Drugs. 1989 Oct;38(4):551-90. doi: 10.2165/00003495-198938040-00005.PubMed: 2573505
  3. 3 . Echizen H, Ishizaki T: Clinical pharmacokinetics of famotidine. Clin Pharmacokinet. 1991 Sep;21(3):178-94. doi: 10.2165/00003088-199121030-00003.PubMed: 1764869
  4. 4 . 29. (2012). In Rang and Dale's Pharmacology (7th ed., pp. 360-363). Edinburgh: Elsevier/Churchill Livingstone.
  5. 5 . FDA Approved Drug Products: PEPCID (famotidine) tablets, for oral use Link
  6. 6 . Mylan Pharmaceuticals Product Monograph: Famotidine, for intravenous injection Link
  7. 7 . Cayman Chemical: Famotidine MSDS Link
  8. 8 . Famotidine - StatPearls - NCBI Bookshelf Link
  9. 9 . Prophylaxis and management of stress ulceration - NCBI Link