What is the best treatment for an 80-year-old patient with impaired renal function, edema, infected leg wounds, and severe pruritus (itchiness) who is experiencing agitation and is currently taking cetirizine (20 mg/day) and Benadryl (diphenhydramine) (25 mg tid po)?

Management of Severe Pruritus and Agitation in an 80-year-old Patient with Renal Failure

Gabapentin is the most appropriate treatment for severe pruritus and agitation in this elderly patient with renal failure, infected leg wounds, and current antihistamine therapy that is proving inadequate. 1

Current Situation Assessment

• The patient is experiencing severe pruritus causing agitation despite:
  • Cetirizine 20mg daily (non-sedating antihistamine)
  • Diphenhydramine 25mg three times daily (sedating antihistamine) 2
• Complicating factors:
  • Advanced age (80 years)
  • Renal failure (impaired kidney function)
  • Edema
  • Infected leg wounds with antibiotic reaction

Treatment Recommendations

First-line Treatment:

1. Optimize current management:

   • Ensure adequate dialysis if applicable
   • Normalize calcium-phosphate balance
   • Control parathyroid hormone levels
   • Correct anemia with erythropoietin if present
   • Apply simple emollients for skin dryness 1

2. Add gabapentin:

   • Start at low dose (100-300mg after dialysis) and titrate slowly
   • Adjust dosing based on renal function
   • Monitor for side effects (dizziness, somnolence) 1, 3
   • Gabapentin is recommended for uremic pruritus and has the advantage of addressing both pruritus and agitation 1

Alternative/Adjunctive Treatments:

1. Consider topical therapies:

   • Moderate to high-potency topical corticosteroids for localized areas
   • Topical capsaicin cream (0.025-0.075%)
   • Topical calcipotriol 1

2. Phototherapy:

   • Broadband UVB (BB-UVB) is an effective treatment for uremic pruritus (Strength of recommendation A) 1

3. For agitation management if gabapentin is insufficient:

   • Consider mirtazapine (15-30mg at bedtime) which can address both pruritus and agitation 4
   • Low-dose lorazepam may be considered for severe agitation, but use cautiously due to age and renal impairment 1

Medications to Avoid or Discontinue

1. Discontinue diphenhydramine:

   • Sedative antihistamines may predispose to dementia with long-term use in elderly
   • Limited clearance in renal failure increases risk of side effects
   • May worsen confusion and agitation 1, 2

2. Adjust cetirizine:

   • Evidence suggests cetirizine is not effective in uremic pruritus
   • Consider discontinuing as it provides minimal benefit 1

3. Avoid gabapentin in hepatic pruritus:

   • Not applicable to this patient with renal failure 1

Dosing Considerations for Renal Impairment

• Gabapentin:

  • Almost exclusively eliminated by renal excretion
  • Requires significant dose reduction in renal impairment
  • Start at lowest possible dose and titrate slowly based on creatinine clearance 5
  • For severe renal impairment: 100-300mg after each dialysis session 5

• Mirtazapine (if needed):

  • Start at 7.5mg at bedtime and titrate cautiously 4

Monitoring and Follow-up

• Assess response to therapy after 2 weeks
• Monitor for medication side effects, particularly sedation and dizziness
• Evaluate wound healing progress and infection status
• Adjust medication dosing based on renal function parameters

Special Considerations

• Elderly patients have increased risk of adverse drug reactions and require careful dose selection 5
• The combination of pruritus and agitation significantly impacts quality of life and requires prompt management 3
• Renal transplantation is the only definitive treatment for uremic pruritus but may not be feasible in this elderly patient 1