Famotidine Dosing for a 67-pound Male with Urticaria (Hives)
For a 67-pound (30.4 kg) male with urticaria, the recommended dose of famotidine is 0.5 mg/kg/dose, which equals approximately 15 mg given twice daily. 1
Dosing Rationale and Calculation
Famotidine is an H2-receptor antagonist that can be used as part of the treatment approach for urticaria. When calculating the appropriate dose:
- Weight-based dosing: 0.5 mg/kg/dose
- Patient weight: 67 pounds = 30.4 kg
- Calculated dose: 30.4 kg × 0.5 mg/kg = 15.2 mg per dose
- Practical dose: 15 mg twice daily
Treatment Approach for Urticaria
First-line Treatment
- Second-generation H1-antihistamines should be the primary treatment for urticaria 1
- Examples: cetirizine 10 mg, loratadine 10 mg, or fexofenadine 180 mg daily
- For children: weight-appropriate dosing of these medications
Role of H2-Antagonists (Famotidine)
- Famotidine can be added as an adjunctive therapy to H1-antihistamines 1, 2
- Studies show famotidine can reduce pruritus and intensity of urticaria without causing significant sedation 2
- Famotidine is approximately 20-50 times more potent than cimetidine and 8 times more potent than ranitidine on a weight basis 3
Escalation of Treatment
If symptoms persist despite standard antihistamine therapy:
- Increase H1-antihistamine dose up to 4 times the standard dose 1
- Add famotidine as adjunctive therapy
- Consider leukotriene receptor antagonists for resistant cases 1
- For severe cases unresponsive to above measures, consider omalizumab or cyclosporine 1
Important Considerations
Monitoring
- Assess treatment response within 1-2 weeks of initiating therapy 1
- Monitor for signs of anaphylaxis, which would require immediate epinephrine administration 1
Potential Pitfalls
- Avoid sedating (first-generation) antihistamines, especially in children and elderly patients, due to cognitive impairment risk 1
- Famotidine is primarily eliminated by the kidneys (72% of the dose recovered unchanged in urine), so dose adjustment may be needed in renal impairment 4
- Long-term use of oral corticosteroids should be avoided, especially in children 1
Patient Education
- Identify and avoid potential triggers for urticaria 1
- Educate regarding signs and symptoms of anaphylaxis 1
- Advise that individual urticarial lesions typically last 2-24 hours; persistence beyond 24 hours may suggest urticarial vasculitis requiring different management 1
By combining H1-antihistamines with famotidine at the appropriate dose, most patients with urticaria will experience significant symptom relief. If symptoms persist, escalation to higher antihistamine doses or additional therapies should be considered.