Drug information of Famotidin


Drug group:

Famotidine is a histamine receptor blocker that inhibits stomach acid production. It is commonly used in the treatment of peptic ulcer disease and gastroesophageal reflux disease .

Mechanism of effect

Famotidine binds competitively to H2-receptors located on the basolateral membrane of the parietal cell, blocking histamine affects. This competitive inhibition results in reduced basal and nocturnal gastric acid secretion and a reduction in gastric volume, acidity, and amount of gastric acid released in response to stimuli including food, caffeine, insulin, betazole, or pentagastrin.


Famotidine is a competitive inhibitor of histamine H2–receptors. The primary clinically important pharmacologic activity of famotidine is inhibition of gastric secretion. Both the acid concentration and volume of gastric secretion are suppressed by famotidine , while changes in pepsin secretion are proportional to volume output. Other action of famotidine includes an increase in gastric bacterial flora such as nitrate-reducing organisms.


- Absorption
• Bioavailability: 40-45% (PO; minimal 1st-pass metabolism)
• Onset: <1 hr (PO); <30 min (IV)
• Duration: 10-12 hr
• Peak plasma time: IV, 20 min; PO, 1-4 hr
- Distribution
• Protein bound: 15-20%
• Vd: 1.1-1.4 L/kg (Adults); 1.5-2.07 L/kg (children); 1.4-1.8 L/kg (infants <3 months); 2.3 L/kg (infants 3-12 months)
- Metabolism
Metabolized in liver Metabolites: Famotidine S-oxide (inactive)
• Half-life: 2.5-4 hr (adults; increases with renal impairment; eg, 20 hr with CrCl <10 mL/min); 3-4 hr (children); 4.5 hr (infants 3-12 months); 8-10.5 hr (infants < 3 months)
• Dialyzable: No
• Renal clearance: 250-450 mL/min
• Total body clearance: 381-483 mL/min
• Excretion: Urine (25-30% as unchanged drug when administered PO; 70% when adminsitered IV)


Pathological Hypersecretory Conditions (e.g., Zollinger-Ellison Syndrome, Multiple Endocrine Adenomas)
The dosage of famotidine in patients with pathological hypersecretory conditions varies with the individual patient. The recommended adult oral starting dose for pathological hypersecretory conditions is 20 mg q 6 h.
In some patients, a higher starting dose may be required. Doses should be adjusted to individual patient needs and should continue as long as clinically indicated. Doses up to 160 mg q 6 h have been administered to some adult patients with severe Zollinger-Ellison Syndrome.
Duodenal Ulcer
- Acute Therapy: The recommended adult oral dosage for active duodenal ulcer is 40 mg once a day at bedtime. Most patients heal within 4 weeks; there is rarely reason to use PEPCID at full dosage for longer than 6 to 8 weeks. A regimen of 20 mg b.i.d. is also effective.
Maintenance Therapy: The recommended adult oral dose is 20 mg once a day at bedtime.
Benign Gastric Ulcer
Acute Therapy: The recommended adult oral dosage for active benign gastric ulcer is 40 mg once a day at bedtime.
Gastroesophageal Reflux Disease (GERD)
The recommended oral dosage for treatment of adult patients with symptoms of GERD is 20 mg b.i.d. for up to 6 weeks. The recommended oral dosage for the treatment of adult patients with esophagitis including erosions and ulcerations and accompanying symptoms due to GERD is 20 or 40 mg b.i.d. for up to 12 weeks.
Dosage For Pediatric Patients < 1 Year Of Age
Gastroesophageal Reflux Disease (GERD)
0.5 mg/kg/dose of famotidine oral suspension for the treatment of GERD for up to 8 weeks once daily in patients < 3 months of age and 0.5 mg/kg/dose twice daily in patients 3 months to < 1 year of age. Patients should also be receiving conservative measures (e.g., thickened feedings). The use of intravenous famotidine in pediatric patients < 1 year of age with GERD has not been adequately studied.
Dosage For Pediatric Patients 1-16 Years Of Age
Peptic ulcer - 0.5 mg/kg/day p.o. at bedtime or divided b.i.d. up to 40 mg/day.
Gastroesophageal Reflux Disease with or without esophagitis including erosions and ulcerations - 1.0 mg/kg/day p.o. divided b.i.d. up to 40 mg b.i.d.
While published uncontrolled studies suggest effectiveness of famotidine in the treatment of gastroesophageal reflux disease and peptic ulcer, data in pediatric patients are insufficient to establish percent response with dose and duration of therapy. Therefore, treatment duration (initially based on adult duration recommendations) and dose should be individualized based on clinical response and/or pH determination (gastric or esophageal) and endoscopy.
Published uncontrolled clinical studies in pediatric patients 1-16 years of age have employed doses up to 1 mg/kg/day for peptic ulcer and 2 mg/kg/day for GERD with or without esophagitis including erosions and ulcerations.


- Famotidine can cause a severe allergic reaction. Symptoms can include:
trouble breathing, swelling in your eye(s) or face, swelling of your throat or tongue, rash, hives
- If you have kidney problems, you may not be able to clear this drug from your body. This may increase the levels of this drug in your body. The increased levels may cause more side effects, such as confusion and an irregular heart rhythm called QT prolongation.
- Famotidine may pass into breast milk and may cause side effects in a child who is breastfed.

Points of recommendation

- May be taken with or without food.
- Antacids may also be used when needed with famotidine for the relief of gastric acid-associated pain.
- Take this drug at the time(s) recommended by your doctor.
- You can cut or crush the tablet.

Pregnancy level


Related drugs

Ranitidine , Cimetidine , Nizatidine

Ask a Pharmacist

User's questions
    No comments yet.