Classes
DEA Class; Rx, OTC
Common Brand Names; Pepcid AC, Zantac 360
- Histamine H2 Antagonists
Description
Oral/parenteral histamine type 2-receptor antagonist
Used for GI disorders such as peptic ulcer and gastroesophageal reflux disease
Fewer drug interactions than cimetidine
Indications
Indicated for
- Duodenal Ulcer
- Benign Gastric Ulcer
- Gastroesophageal Reflux Disease
- Hypersecretory Conditions
- Heartburn
Contraindications
Hypersensitivity to famotidine or other H2-receptor antagonists
Adverse Effects
- Headache (4.7%)
- Diarrhea (1.7%)
- Dizziness (1.3%)
- Constipation (1.2%)
Warnings
Use caution in renal impairment; dosage adjustment recommended in moderate to severe renal impairment (CrCl <50 mL/min)
Prolonged QT interval reported rarely in patients with renal impairment whose dose or dosing interval may not have been adjusted appropriately
Central nervous system (CNS) adverse effects, including confusion, delirium, hallucinations, disorientation, agitation, seizures, and lethargy, reported with moderate-to-severe renal impairment; since famotidine blood levels are higher in patients with renal impairment than in patients with normal renal function, dosage adjustments are recommended in patients with renal impairment
Relief of symptoms does not eliminate the presence of gastric malignancy; consider evaluation for gastric malignancy in adult patients who have a suboptimal response or an early symptomatic relapse after completing treatment
State of confusion reported with use; risk increased in >50 years of age and/or renal/hepatic impairment
Prolonged treatment (>2 years) may lead to vitamin B12 malabsorption, which can result in vitamin B12 deficiency; magnitude of deficiency is dose related; occurs most frequently in females and those younger then 30 years
Patients should not use OTC if difficulty swallowing, vomiting blood, have bloody or black stools
If patient taking a prescription drug, the patient should ask a doctor or a pharmacist whether acid reducers can be taken concomitantly with it
Patients with kidney disease should ask doctor before use
Pregnancy and Lactation
Available data in pregnant women are insufficient to establish a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes
There are limited data available on presence in human breast milk; there were no effects on breastfed infant; there are no data on famotidine effects on milk production
Maximum Dosage
40 mg/day PO or IV for active duodenal or benign gastric ulcer; 20 mg/day PO for ulcer maintenance; 40 mg/day PO for GERD; 80 mg/day PO for esophagitis; doses may go as high as 640 mg/day or 800 mg/day (rare) PO or 80 mg/day IV for hypersecretory conditions such as Zollinger-Ellison; 40 mg/day PO for self-medication (OTC).
40 mg/day PO or IV for active duodenal or benign gastric ulcer healing; 20 mg/day PO for ulcer maintenance; 40 mg/day PO for GERD; 80 mg/day PO for esophagitis; doses may go as high as 640 mg/day or 800 mg/day (rare) PO or 80 mg/day IV for hypersecretory conditions such as Zollinger-Ellison; 40 mg/day PO for self-medication (OTC).
1 mg/kg/day PO (Max: 80 mg/day); 1 mg/kg/day IV (Max: 40 mg/day) is FDA-approved maximum; however, doses up to 2 mg/kg/day IV have been used off-label.
1 mg/kg/day PO (Max: 80 mg/day); 1 mg/kg/day IV (Max: 40 mg/day) is FDA-approved maximum; however, doses up to 2 mg/kg/day IV have been used off-label.
3 to 11 months: 2 mg/kg/day PO. Safety and efficacy of IV have not been established; however, doses up to 2 mg/kg/day IV have been used off-label.
1 to 2 months: 1 mg/kg/day PO. Safety and efficacy of IV have not been established; however, doses up to 2 mg/kg/day IV have been used off-label.
1 mg/kg/day PO. Safety and efficacy of IV have not been established; however, 0.5 mg/kg/day IV has been used off-label.
How supplied
Famotidine
injection solution (Rx)
- 10mg/mL
- 0.4mg/mL
oral suspension (Rx)
- 40mg/5mL (generic)
tablet (OTC)
- 10mg (Pepcid AC, Zantac 360, generic)
- 20mg (Pepcid AC, Zantac 360, generic)
- 40mg (Pepcid AC, generic)
tablet, chewable (OTC)
- 10mg (Pepcid AC, generic)
- 20mg (Pepcid AC)
