Brand and Other Names:Pepcid, Act, more...Dyspep HB, Fluxid, Acid Controller
- Classes: Histamine H2 Antagonists
Dosing & Uses
Dosage Forms & Strengths
Acute treatment: 20 mg PO/IV q12hr or 40 mg PO at bedtime for 4-8 weeks
Maintenance: 20 mg PO at bedtime
Benign Gastric Ulcer
40 mg PO at bedtime
Gastroesophageal Reflux Disease
20 mg PO q12hr for 6 weeks
With esophagitis: 20-40 mg PO q12hr for up to 12 weeks
20 mg PO/IV q6hr; may increase up to 160 mg q6hr
10-20 mg q12 hr; may take 15-60 min before eating foods that could cause heartburn
CrCl <50 mL/min: Give 50% of usual dose, or prolong dosing interval to q36-48hr
Dosage Forms & Strengths
Gastroesophageal Reflux Disease
3-12 months: 0.5 mg/kg PO q12hr for up to 8 weeks
1-16 years: 1 mg/kg/day PO divided q12hr; individual dose not to exceed 40 mg
<12 years: Not established
>12 years: 10-20 mg q12 hr; may take 15-60 min before eating foods that could cause heartburn
Serious - Use Alternative
Significant - Monitor Closely
Frequency Not Defined
Body as a whole: Fever, asthenia, fatigue
Cardiovascular: Arrhythmia, AV block, palpitation; prolonged QT interval in patients with impaired renal function, has been reported very rarely
Gastrointestinal: Cholestatic jaundice, hepatitis, liver enzyme abnormalities, vomiting, nausea, abdominal discomfort, anorexia, dry mouth
Hematologic: Rare cases of agranulocytosis, pancytopenia, leukopenia, thrombocytopenia
Hypersensitivity: Anaphylaxis, angioedema, orbital or facial edema, urticaria, rash, conjunctival injection
Musculoskeletal: Rhabdomyolysis, musculoskeletal pain including muscle cramps, arthralgia
Nervous system/psychiatric: Grand mal seizure; psychic disturbances, which were reversible in cases for which follow-up was obtained, including hallucinations, confusion, agitation, depression, anxiety, decreased libido; paresthesia; insomnia; somnolence; convulsions, in patients with impaired renal function, have been reported very rarely
Respiratory: Bronchospasm, interstitial pneumonia
Skin: Toxic epidermal necrolysis/Stevens-Johnson syndrome (very rare), alopecia, acne, pruritus, dry skin, flushing
Special senses: Tinnitus, taste disorder
Rare cases of impotence and rare cases of gynecomastia
Hypersensitivity to famotidine or other H2-receptor antagonists
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 reported with moderate-to-severe renal impairment
Relief of symptoms does not eliminate the presence of gastric malignancy
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
Not for OTC use with other acid reducers
Pregnancy & Lactation
Pregnancy category: B
Lactation: Drug enters breast milk; use not recommended
A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA:Information not available.
Mechanism of Action
Blocks H2 receptors of gastric parietal cells, leading to inhibition of gastric secretions
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
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)
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)
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)
Y-site: Cefepime, piperacillin-tazobactam, amphotericin B, azithromycin, furosemide (at 2 mg/mL famotidine; compatible at 0.2 mg/mL)
Additive: Aztreonam, ceftazidime, dobutamine, dopamine, furosemide, gentamicin, imipenem, thiamine
Y-site: Atropine, cefazolin, furosemide, gentamicin, heparin, norepinephrine, thiamine
Dilute 20 mg to total of 5 or 10 mL with NS, D5W, or LR
Also available in premixed bag containing 20 mg in 50 mL NS
Infuse at rate no faster than 10 mg/min
Premixed: Store at room temperature
Unmixed: Store in refrigerator at 2-8°C (36-46°F)
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