What is the recommended dosing of famotidine (H2 receptor antagonist) for patients with Chronic Kidney Disease (CKD)?

Famotidine Dosing in Chronic Kidney Disease

For patients with chronic kidney disease (CKD), famotidine dosing should be reduced based on creatinine clearance, with patients having severe renal impairment (CrCl <30 mL/min) requiring a 75% dose reduction to 20 mg every other day. 1

Dosing Recommendations Based on Renal Function

Normal Renal Function

• Standard dosing: 20-40 mg once daily or 20 mg twice daily (depending on indication)

Moderate Renal Impairment (CrCl 30-60 mL/min)

• Reduce to 20 mg once daily or 40 mg every other day 1
• This represents a 50% dose reduction from normal dosing

Severe Renal Impairment (CrCl <30 mL/min)

• Reduce to 20 mg every other day 1
• This represents a 75% dose reduction from normal dosing

End-Stage Renal Disease/Hemodialysis

• Maintain at 20 mg every other day
• No supplemental dose is required after dialysis as famotidine is only moderately removed by hemodialysis 2

Pharmacokinetic Rationale

The need for dosage adjustment is based on the following pharmacokinetic changes in CKD:

• Elimination half-life: Increases from 2.6 hours in normal renal function to:

  • 4.7 hours in moderate renal impairment
  • 12.1 hours in severe renal impairment
  • Up to 27.2 hours in end-stage renal disease 3, 2

• Renal clearance: Significantly reduced in proportion to declining kidney function 4

  • Normal: ~310 mL/min
  • Decreases proportionally with declining creatinine clearance

• Excretion: Approximately 70% of famotidine is normally excreted through the kidneys, primarily via tubular secretion 3

Clinical Considerations

1. Monitoring: Patients with CKD receiving famotidine should be monitored for:

   • Signs of CNS toxicity (headache, confusion, agitation)
   • QT prolongation (particularly in those with other risk factors)
   • Drug interactions (especially with medications that are also renally cleared)

2. Alternative H2 Blockers: While all H2 blockers require dose adjustment in CKD, famotidine is generally preferred over cimetidine due to fewer drug interactions

3. Common Pitfalls to Avoid:

   • Failing to reassess renal function during prolonged therapy
   • Not accounting for age-related decline in renal function (elderly patients often require dose reduction even with normal serum creatinine)
   • Using standard doses in acute kidney injury

Special Situations

• Elderly Patients: Consider dose reduction even with normal serum creatinine due to age-related decline in renal function 4
• Patients on Continuous Renal Replacement Therapy: May require less aggressive dose reduction than those with static severe CKD 2

Following these guidelines will help optimize the efficacy of famotidine while minimizing potential adverse effects in patients with chronic kidney disease.