What is the recommended dosing for famotidine (Histamine-2 (H2) blocker) in adults with Gastroesophageal Reflux Disease (GERD) or peptic ulcer disease?

Famotidine Dosing for GERD and Peptic Ulcer Disease

For GERD, use famotidine 20 mg twice daily; for active peptic ulcers, use 40 mg once daily at bedtime or 20 mg twice daily. 1

Standard Dosing by Indication

Active Duodenal Ulcer

• 40 mg once daily at bedtime OR 20 mg twice daily for up to 8 weeks 1
• Both regimens demonstrate equivalent effectiveness, with 70% healing at 4 weeks and 83% at 8 weeks 1, 2
• Most patients heal within 4 weeks; if not healed, consider an additional 2-4 weeks of treatment 1
• Take once-daily dosing before bedtime 1

Active Gastric Ulcer

• 40 mg once daily at bedtime for up to 8 weeks 1
• Achieves 78-80% healing rates by week 8 1

Symptomatic Non-Erosive GERD

• 20 mg twice daily for up to 6 weeks 1
• This twice-daily regimen is superior to 40 mg at bedtime (82% vs 69% improvement at 6 weeks) 1
• The twice-daily dosing is necessary because H2-receptor antagonists have acid-inhibiting effects lasting approximately 6 hours 3

Erosive Esophagitis (Endoscopically Confirmed)

• 20 mg twice daily OR 40 mg twice daily for up to 12 weeks 1
• The 40 mg twice daily regimen shows superior healing: 48% at 6 weeks and 69% at 12 weeks compared to 32% and 54% with 20 mg twice daily 1
• For severe or refractory cases, use the higher dose regimen 1

Duodenal Ulcer Recurrence Prevention

• 20 mg once daily at bedtime for up to 1 year 1
• Reduces recurrence rate to 23% compared to 57% with placebo 1

Pathological Hypersecretory Conditions (Zollinger-Ellison)

• Starting dose: 20 mg every 6 hours, titrated to individual needs 1
• Maximum dose: 160 mg every 6 hours 1
• Adjust to maintain basal acid secretion below 10 mEq/hour 1

Administration Guidelines

• Timing: Take once-daily doses before bedtime; twice-daily doses in the morning and before bedtime 1
• May be taken with or without food 1
• Can be administered with antacids 1

Renal Impairment Adjustments

Moderate Impairment (CrCl 30-60 mL/min)

• Active ulcers or GERD: 20 mg once daily OR 40 mg every other day 1
• Erosive esophagitis: 20 mg once daily OR 40 mg every other day 1

Severe Impairment (CrCl <30 mL/min)

• All indications: 20 mg every other day (or 10 mg once daily using alternate formulation) 1
• Avoid use for pathological hypersecretory conditions due to unknown risk profile 1

Important Clinical Considerations

Efficacy Limitations

• PPIs are more effective than famotidine for esophageal GERD syndromes and should be considered first-line 3
• Tachyphylaxis (decreased response) can develop within 6 weeks of H2-receptor antagonist therapy, limiting long-term effectiveness 3
• If patients fail empirical twice-daily PPI therapy, endoscopy should be performed rather than switching to famotidine 3

Specific Advantages

• Preferred over PPIs in patients on dual antiplatelet therapy (e.g., aspirin plus clopidogrel) due to potential PPI-clopidogrel interactions 3
• Unlike cimetidine, famotidine is not associated with gynecomastia or increased liver disease risk 3
• Does not affect hepatic drug metabolism, avoiding drug-drug interactions seen with cimetidine 4

Stress Ulcer Prophylaxis

• For critically ill patients: ≤40 mg daily 3