Famotidine (Monograph)
Brand name: Pepcid
Drug class: Histamine H2-Antagonists
Introduction
Histamine H2 receptor antagonist.
Uses for Famotidine
Duodenal Ulcer
Short-term treatment of active duodenal ulcer (endoscopically or radiographically confirmed).
Maintenance of healing and reduction in recurrence of duodenal ulcer.
Pathologic GI Hypersecretory Conditions
Treatment of Zollinger-Ellison syndrome, multiple endocrine adenomas.
Gastric Ulcer
Short-term treatment of active benign gastric ulcer.
Gastroesophageal Reflux (GERD)
Short-term treatment of symptomatic GERD.
Short-term treatment of esophagitis, including erosions or ulcers (endoscopically diagnosed) in patients with GERD.
Self-medication as initial therapy for less severe symptomatic GERD† [off-label].
Short-term self-medication for relief of heartburn symptoms in adults and adolescents ≥12 years of age.
Short-term self-medication for prevention of heartburn symptoms associated with acid indigestion and sour stomach brought on by ingestion of certain foods and beverages in adults and children ≥12 years of age.
Famotidine Dosage and Administration
Administration
Administered orally, or by slow IV injection or intermittent IV infusion in hospitalized patients with pathological GI hypersecretory conditions or intractable duodenal ulcer, or when oral therapy is not feasible.
Oral Administration
Administer with or without food; administration with food may slightly enhance bioavailabilty.
Antacids may be used as necessary for pain relief.
Tablet for self-medication should be administered with a glass of water.
Chewable tablets (Pepcid AC Chewable, Pepcid Complete) for self-medication should be chewed thoroughly before swallowing.
For duodenal ulcer treatment, the advantage of administration once daily at bedtime (when convenience is important for compliance) over twice-daily administration has not been determined.
For gastric ulcer treatment in adults, administer once daily at bedtime.
For gastroesophageal reflux, once daily dosage not considered appropriate.
Oral Suspension
Add 46 mL of water to bottle containing 400 mg of famotidine for 40 mg/5mL suspension.
Shake oral suspension vigorously for 5–10 seconds after reconstitution and before each use.
Intermittent Direct IV Injection
Dilution
Dilute 20 mg to 5–10 mL with 0.9% sodium chloride injection or other compatible IV solution before direct IV injection.
Rate of Administration
Inject over not less than 2 minutes (no faster than 10 mg/minute).
Intermittent IV infusion
Dilution
Dilute 20 mg in at least 100 mL of 5% dextrose injection or other compatible IV solution.
No additional dilution required for commercially available infusion solution (20 mg famotidine in 50 mL of 0.9% sodium chloride injection).
Rate of Administration
Over 15–30 minutes.
Dosage
Pediatric Patients
General Parenteral Dosage
May administer IV in hospitalized pediatric patients with pathologic hypersecretory conditions, intractable ulcer, or for short-term use when oral therapy is not feasible.
Safety and efficacy have not been established in children <1 year of age.
Treatment of Children 1–16 Years of Age
Individualize duration and dosage based on clinical response and/or gastric or esophageal pH determination and endoscopy.
Intermittent Direct IV InjectionInitially, 0.25 mg/kg (15-minute infusion) every 12 hours (maximum 40 mg daily). Up to 0.5 mg/kg every 12 hours has provided gastric acid suppression.
Intermittent IV InfusionInitially, 0.25 mg/kg (over not less than 2 minutes) every 12 hours (maximum 40 mg daily). Up to 0.5 mg/kg every 12 hours has provided gastric acid suppression
Gastroesophageal Reflux
Treatment of GERD in Infants <3 Months of Age
Oral0.5 mg/kg once daily for up to 4 weeks.
Infants should also be receiving conservative measures (e.g., thickened feedings).
IVSafety and efficacy not established.
Treatment of GERD in Infants 3 Months to <1 Year of Age
Oral0.5 mg/kg twice daily for up to 4 weeks.
Infants should also be receiving conservative measures (e.g., thickened feedings).
IVSafety and efficacy not established.
Treatment of GERD in Children 1–16 Years of Age
Oral1 mg/kg daily in 2 divided doses (maximum 40 mg twice daily); up to 2 mg/kg daily has been used.
Individualize duration and dosage based on clinical response and/or gastric or esophageal pH determination and endoscopy.
IVDosage not established.
Treatment of Esophagitis in Children 1- 16 Years of Age
Oral1 mg/kg daily in 2 divided doses (maximum 40 mg twice daily); up to 2 mg/kg daily has been used.
Individualize duration and dosage based on clinical response and/or gastric or esophageal pH determination and endoscopy.
IVDosage not established.
Self-medication for Heartburn in Adolescents ≥12 Years of Age
Oral10-mg tablets: 10 mg once or twice daily (maximum 20 mg in 24 hours continuously for 2 weeks) or as directed by clinician.
Chewable tablets: 10 mg once or twice daily (maximum 20 mg in 24 hours continuously for 2 weeks) or as directed by clinician. Do not swallow whole; chew completely before swallowing.
20-mg tablets: 20 mg once or twice daily (maximum 40 mg in 24 hours continuously for 2 weeks) or as directed by clinician.
Fixed combination of famotidine, calcium carbonate, and magnesium hydroxide (Pepcid Complete): 1 tablet (10 mg of famotidine) once or twice daily (maximum 2 tablets in 24 hours continuously for 2 weeks). Do not swallow whole; chew completely before swallowing.
Self-medication for Prevention of Heartburn In Adolescents ≥12 Years of Age
Oral10-mg tablets: 10 mg once or twice daily (15–60 minutes before ingestion of causative food or beverage); maximum 20 mg in 24 hours continuously for 2 weeks or as directed by clinician.
10-mg chewable tablets: 10 mg once or twice daily (15–60 minutes before ingestion of causative food or beverage); maximum 20 mg in 24 hours continuously for 2 weeks or as directed by clinician. Do not swallow whole; chew completely before swallowing.
20-mg tablets: 20 mg once or twice daily (10–60 minutes before ingestion of causative food or beverage); maximum 40 mg in 24 hours continuously for 2 weeks or as directed by clinician.
Duodenal Ulcer
Treatment of Duodenal Ulcer in Children 1–16 Years of Age
Oral0.5 mg/kg once daily at bedtime or in 2 divided doses daily (maximum 40 mg daily); up to 1 mg/kg daily has been used.
Individualize duration and dosage based on clinical response and/or gastric or esophageal pH determination and endoscopy.
Gastric Ulcer
Treatment of Gastric Ulcer in Children 1–16 Years of Age
Oral0.5 mg/kg once daily at bedtime or in 2 divided doses daily (maximum 40 mg daily); up to 1 mg/kg daily has been used.
Individualize duration and dosage based on clinical response and/or gastric or esophageal pH determination and endoscopy.
Adults
General Parenteral Dosage
May administer IV in hospitalized adults with pathologic hypersecretory conditions, intractable ulcer, or for short-term use when oral therapy is not feasible.
Dosage for parenteral administration in patients with GERD has not been established.
Intermittent Direct IV Injection
20 mg every 12 hours (maximum 40 mg daily).
Intermittent IV Infusion
20 mg every 12 hours (maximum 40 mg daily).
Gastroesophageal Reflux
Treatment of GERD
Oral20 mg twice daily for up to 6 weeks.
40 mg once daily at bedtime also has been used, but is less effective and not considered appropriate therapy.
Treatment of Esophagitis
Oral20 or 40 mg twice daily for up to 12 weeks.
Self-medication for Heartburn
Oral10-mg tablets: 10 mg once or twice daily (maximum 20 mg in 24 hours continuously for 2 weeks) or as directed by clinician.
Chewable tablets: 10 mg once or twice daily (maximum 20 mg in 24 hours continuously for 2 weeks) or as directed by clinician. Do not swallow whole; chew completely before swallowing.
Fixed combination of famotidine, calcium carbonate, and magnesium hydroxide (Pepcid Complete): 1 tablet (10 mg of famotidine) once or twice daily (maximum 2 tablets in 24 hours continuously for 2 weeks). Do not swallow whole; chew completely before swallowing.
20-mg tablets: 20 mg once or twice daily (maximum 40 mg in 24 hours continuously for 2 weeks) or as directed by clinician.
Self-medication for Prevention of Heartburn
Oral10-mg tablets: 10 mg once or twice daily (15–60 minutes before ingestion of causative food or beverage); maximum 20 mg in 24 hours continuously for 2 weeks or as directed by clinician.
Chewable tablets: 10 mg once or twice daily (15–60 minutes before ingestion of causative food or beverage); maximum 20 mg in 24 hours continuously for 2 weeks or as directed by clinician. Do not swallow whole; chew completely before swallowing.
20-mg tablets: 20 mg once or twice daily (10–60 minutes before ingestion of causative food or beverage); maximum 40 mg in 24 hours continuously for 2 weeks or as directed by clinician .
Duodenal Ulcer
Treatment of Active Duodenal Ulcer
Oral40 mg once daily at bedtime, or 20 mg twice daily.
Healing may occur within 2 weeks in some, and within 4 weeks in most patients; some patients may benefit from an additional 4 weeks of therapy.
Occasionally may be necessary to continue full-dose therapy for >6–8 weeks.
Safety and efficacy of continuing full-dose therapy for >8 weeks have not been established.
Maintenance of Healing of Duodenal Ulcer
Oral20 mg once daily at bedtime.
Gastric Ulcer
Oral
40 mg daily at bedtime for up to 8 weeks.
Complete healing of gastric ulcers usually occurs within 8 weeks.
Safety and efficacy of therapy for >8 weeks have not been established.
Pathologic GI Hypersecretory Conditions
Zollinger-Ellison Syndrome
Oral20 mg every 6 hours. Higher doses administered more frequently may be necessary; adjust dosage according to response and tolerance and continue as long as necessary.
20–160 mg every 6 hours generally has been necessary to maintain basal gastric acid secretion at <10 mEq/hour.
Up to 160 mg every 6 hours, or 800 mg daily in divided doses, has been used in severe disease.
Intermittent IV Infusion20 mg every 12 hours. Higher initial dosage may be required; adjust to individual needs and continue as long as necessary.
Prescribing Limits
Pediatric Patients
General Parenteral Dosage
Treatment of children 1–16 Years of Age
Intermittent Direct IV InjectionMaximum 40 mg daily.
Intermittent IV InfusionMaximum 40 mg daily.
Gastroesophageal Reflux
Treatment of GERD in Infants <1 Year of Age
OralSafety and efficacy for >4 weeks not established.
Treatment of GERD without Esophagitis in Children 1–16 Years of Age
OralMaximum 40 mg twice daily.
Treatment of Esophagitis (including Erosions, Ulcerations) in Children 1- 16 Years of Age
OralMaximum 40 mg twice daily.
Self-Medication For Heartburn in Adolescents ≥12 Years of Age
OralMaximum 20 or 40 mg in 24 hours continuously for 2 weeks.
Self-medication for Prevention of Heartburn in Adolescents ≥12 Years of Age
OralMaximum 20 or 40 mg in 24 hours continuously for 2 weeks.
Duodenal Ulcer
Treatment of Active Duodenal Ulcer in Children 1–16 Years of Age
OralMaximum 40 mg daily.
Gastric Ulcer
Treatment of Gastric Ulcer in Children 1–16 Years of Age
OralMaximum 40 mg daily.
Adults
General Parenteral Dosage
Intermittent Direct IV Injection
Maximum 40 mg daily.
Intermittent IV Infusion
Maximum 40 mg daily.
Gastroesophageal Reflux
Treatment of Symptomatic GERD
OralSafety and efficacy for >6 weeks not established.
Treatment of Esophagitis
OralSafety and efficacy for >12 weeks not established.
Self-medication for Heartburn
OralMaximum 20 or 40 mg in 24 hours continuously for 2 weeks.
Self-medication for Prevention of Heartburn
Maximum 20 or 40 mg in 24 hours continuously for 2 weeks.
Duodenal Ulcer
Treatment of Active Duodenal Ulcer
OralSafety for >8 weeks not established.
Gastric Ulcer
Short-term Treatment of Active Benign Gastric Ulcer
OralSafety and efficacy for >8 weeks not established.
Pathologic GI Hypersecretory Conditions (e.g., Zollinger-Ellison Syndrome)
Oral
Up to 160 mg every 6 hours, or 800 mg daily in divided doses.
Special Populations
Renal Impairment
Pediatric Patients
Consider dosage adjustment in children with moderate or severe renal impairment.
Adults
In adults, modify dose and/or frequency of administration to the degree of renal impairment; adverse CNS effects have been reported.
Moderate (Clcr<50 mL/minute) or Severe (Clcr< 10 mL/minute)
OralDecrease to 50% of usual dosage.
Alternatively, increase dosing interval to 36–48 hours according to response.
IVDecrease to 50% of usual dosage.
Alternatively, increase dosing interval to 36–48 hours according to response.
Clcr of 30–60 mL/minute per 1.48 m2
50% of usual adult dosage has been recommended.
Clcr < 30 mL/minute per 1.48 m2
25% of usual adult dosage has been recommended.
Cautions for Famotidine
Contraindications
-
Known hypersensitivity to famotidine, any ingredient in the formulation, or to other histamine H2 antagonists (i.e., cimetidine, nizatidine, ranitidine).
Warnings/Precautions
General Precautions
Gastric Malignancy
Response to famotidine does not preclude presence of gastric malignancy.
Phenylketonuria
Pepcid AC chewable tablets contain aspartame (Nutrasweet), which is metabolized in the GI tract to provide 1.4 mg of phenylalanine per tablet.
Respiratory Effects
Administration of H2-receptor antagonists has been associated with an increased risk for developing certain infections (e.g., community-acquired pneumonia).
Use of Fixed Combination
When used in fixed combination with other agents, consider the cautions, precautions, and contraindications associated with the concomitant agents.
Specific Populations
Pregnancy
Category B.
Self-medication in pregnant women: consult clinician before using.
Lactation
Distributed into milk. Discontinue nursing or the drug.
Self-medication in nursing women: consult clinician before using.
Pediatric Use
Infants <1 year of age: Consider for GERD treatment only if other conservative measures (e.g., thickened feedings) are used concurrently and potential benefits outweigh risks.
Safety and efficacy for self-medication not established in children <12 years of age; do not use unless directed by clinician.
Renal Impairment
Use with caution. Dosage adjustments necessary in patients with severe renal impairment.
Common Adverse Effects
Headache, dizziness, constipation, diarrhea.
Drug Interactions
Does not appear to inhibit hepatic metabolism of drugs by hepatic CYP isoenzymes.
Antacids appear to cause slight but clinically unimportant decrease in bioavailability. May concomitantly administer with antacids.
Famotidine Pharmacokinetics
Absorption
Bioavailability
Oral: about 40–50%. Similar (50%) in children 11–15 years of age.
Tablets and oral suspension reportedly are bioequivalent.
Onset
Gastric acid inhibition within 1 hour after IV or oral administration. Peak inhibition within 0.5–3 hours following IV, 1–4 hours following oral administration.
Duration
Dose-dependent inhibition of gastric acid secretion.
Inhibition of basal and nocturnal secretion for 10–12 hours after single oral 20- or 40-mg dose.
Inhibition of food-stimulated secretion generally persists for 8–10 hours after morning administration, but may dissipate within 6–8 hours after a 20-mg oral dose in some patients.
Inhibition of nocturnal gastric acid secretion is 10–15 hours after single 10- or 20-mg IV dose.
Food
May slightly enhance bioavailability.
Distribution
Extent
Widely distributed, highest concentrations in the kidney, liver, pancreas, and submandibular gland.
Distributed into human milk.
Does not cross the placenta in animal studies; not known if famotidine crosses the placenta in humans.
Plasma Protein Binding
15–20%.
Elimination
Metabolism
Metabolized in the liver to inactive famotidine S-oxide (S-famotidine).
Minimal first-pass metabolism.
Elimination Route
Excreted principally in urine; 25–30% excreted unchanged within 24 hours after oral administration, 65–80% after IV administration. Small fraction of orally administered dose is excreted in urine as famotidine S-oxide. Remainder of orally administered dose eliminated in feces.
Interindividual variation in metabolism and excretion.
Half-life
2.5–4 hours (adults).
Special Populations
In patients with renal impairment, close correlation between Clcr and elimination half-life; >20 hours when Clcr <10 mL/minute, 24 hours in anuric patients.
Does not appear to be removed by hemodialysis.
Stability
Storage
Oral
Tablets
20 and 40 mg film-coated tablets: 25°C (may be exposed to 15–30°C) in tight, light-resistant containers.
Tablets for Self-medication
10 mg tablets, chewable tablets, film-coated tablets: 25–30°C.
10 mg chewable tablets in combination with calcium carbonate and magnesium hydroxide: 25–30°C.
20 mg film-coated tablets: 20–30°C.
Protect from moisture.
For Suspension
Reconstituted suspension or dry powder: 25°C (may be exposed to 15–30°C) in tight containers.
Suspension may be refrigerated; protect from freezing.
Discard unused suspension after 30 days.
Parenteral
Injection
2–8°C; expiration date of 24 months following the date of manufacture when stored at this temperature. If freezing occurs, thaw at room temperature, or in warm water bath, or under running hot tap water; allow sufficient time for dissolution of all ingredients. Do not thaw by microwave because of potential hazard of rapidly increased temperature and vapor pressure in a closed system. Diluted solutions of famotidine not used immediately after preparation should be refrigerated and used within 48 hours.
Injection for IV infusion only
25°C. Protect from excessive heat; brief exposure up to 35°C will not adversely affect the stability of the solution. Stable for 15 months when stored as recommended.
Actions
-
Inhibits daytime, nocturnal basal and stimulated gastric acid secretion.
-
Competitively inhibits histamine at parietal cell H2 receptors.
Advice to Patients
-
Importance of following dosage instructions when famotidine is administered for self-medication, unless otherwise directed by a clinician.
-
Importance of promptly informing clinician of persistent abdominal pain or difficulty swallowing.
-
Importance of patients informing clinician of existing or contemplated concomitant therapy, including prescription and OTC drugs; antacids (calcium carbonate and magnesium hydroxide) in Pepcid Complete may interact with other drugs.
-
Importance of women informing clinician if they are or plan to become pregnant or plan to breast-feed.
-
Importance of informing patients of other important precautionary information.
Additional Information
The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer’s labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.
Preparations
Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.
Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.
* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name
Routes |
Dosage Forms |
Strengths |
Brand Names |
Manufacturer |
---|---|---|---|---|
Oral |
For suspension |
40 mg/5 mL |
Pepcid (with parabens) |
Merck |
Tablets |
10 mg |
Pepcid AC Gelcaps |
J&J-Merck |
|
Tablets, chewable |
10 mg |
Pepcid AC (with aspartame) |
J&J-Merck |
|
Tablets, film-coated |
10 mg |
Pepcid AC |
J&J-Merck |
|
20 mg* |
Pepcid |
Merck |
||
Pepcid AC Maximum Strength |
J&J-Merck |
|||
40 mg |
Pepcid |
Merck |
||
Parenteral |
For injection, concentrate |
10 mg/mL (pharmacy bulk package) |
Famotidine for Injection |
Bedford |
For injection concentrate, for IV use |
10 mg/mL |
Famotidine for Injection |
American Pharmaceutical Partners |
|
Pepcid I.V. (preservative-free; in single-dose vials or with benzyl alcohol 0.9% in multiple-dose vials) |
Merck |
Routes |
Dosage Forms |
Strengths |
Brand Names |
Manufacturer |
---|---|---|---|---|
Parenteral |
Injection, for IV use only |
0.4 mg/mL (20 mg) in 0.9% Sodium Chloride |
Pepcid Premixed in Iso-osmotic Sodium Chloride Injection (Galaxy [Baxter]) |
Merck |
Routes |
Dosage Forms |
Strengths |
Brand Names |
Manufacturer |
---|---|---|---|---|
Oral |
Tablets, chewable |
10 mg with calcium carbonate 800 mg and magnesium hydroxide 165 mg |
Pepcid Complete |
J&J-Merck |
AHFS DI Essentials™. © Copyright 2025, Selected Revisions October 10, 2024. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.
† Off-label: Use is not currently included in the labeling approved by the US Food and Drug Administration.
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