Famotidine

Administration

• Type: Histamine H2 blocker
• Dosage Forms: 10, 20, and 40 PO; 40/5 mL suspension
• Routes of Administration: PO, IV
• Common Trade Names: Pepcid, Pepcid AC

Adult Dosing

Active duodenal ulcer

• 40mg PO qhs x4-6 weeks
• Alt dosing: 20mg PO BID or 20mg IV q12 hr

Maintenance duodenal ulcer

• 20mg PO qhs

Gastric ulcer

• 40mg PO qhs
• Alt dosing: 20mg IV q12 hr

GERD

• 20-40mg PO BID x12 weeks
• Alt dosing: 20mg IV q12 hr

Zollinger-Ellison syndrome

• 20-60mg PO q6 hr
• Alt dosing: 20mg IV q12 hr
• Max: 160mg PO q6 hr

intractable ulcer

• 20mg IV q12 hr

H. pylori infection

• 20mg PO BID x 10-28 days
• Use in combination with other medications for eradication

Pediatric Dosing

PUD

• 1-16 years old
  • 0.5-1mg/kd/day PO daily-bid
  • Start at 0.5mg/kg/day daily-bid
  • Alt dosing: 0.5-1mg/kg/day IV bid
  • Max 40mg/day

GERD

• <3 mo
  • 0.5mg/kg/day PO daily
• 3-12 mo
  • 1mg/kg/day PO bid
• 1-16 yo
  • 1-2mg/kg/day PO bid
  • Start 1mg/kg/day bid
  • Alt dosing: 0.5-1mg/kg/day IV bid
  • Max 40mg/day

Special Populations

• Pregnancy Rating: B
• Lactation risk: Probably safe

Renal Dosing

• Adult: CrCl<50: decrease dose by 50% or give q 36-48 hr; If on dialysis give after dialysis
• Pediatric: CrCl 10-50: decrease dose 50% or give q24 hr, CrCl<10: give q36-48 hr

Hepatic Dosing

• Adult: Not defined
• Pediatric:Not defined

Contraindications

• Allergy to class/drug
• Caution in renal impairment

Adverse Reactions

Serious

• Anaphylaxis
• Angioedema
• TEN
• Stevens-Johnson Syndrome
• agranulocytosis
• leukopenia
• thrombocytopenia
• pancytopenia
• seizures
• AV block
• arrhythmias
• CNS toxicity
• cholestatic jaundice
• hepatitis
• interstitial pneumonia
• QT prolongation

Common

• headache
• dizziness
• constipation
• diarrhea
• taste changes
• vitamin B12 deficiency

Pharmacology

• Half-life: 2.5-3.5 hr; >20 hr with CrCl<10
• Metabolism: minimally liver/CYP450
• Excretion: urine

Mechanism of Action

• Selective histamine H2 blocker