What is the appropriate management of shingles (herpes zoster) in adults, including antiviral therapy, pain control, and vaccination recommendations?

Management of Shingles (Herpes Zoster) in Adults

Start oral antiviral therapy with valacyclovir 1000 mg three times daily or famciclovir 500 mg every 8 hours for 7 days within 72 hours of rash onset to reduce lesion duration, acute pain intensity, and risk of postherpetic neuralgia. 1, 2

Antiviral Therapy

First-Line Oral Regimens

• Valacyclovir 1000 mg three times daily for 7 days is preferred over acyclovir due to more convenient dosing and better bioavailability, though optimal choice depends on renal function 1
• Famciclovir 500 mg every 8 hours for 7 days is equally effective as an alternative to valacyclovir 1, 2
• Both valacyclovir and famciclovir accelerate cutaneous healing and reduce severity of acute pain when administered within 72 hours of rash onset 3
• Dose reduction is required for creatinine clearance < 50 mL/min to avoid toxicity, particularly critical in older adults 2

Intravenous Therapy for Severe Disease

• Intravenous acyclovir 10 mg/kg every 8 hours for 21 days is indicated for central nervous system complications (meningoencephalitis, myelitis) or disseminated disease 2

Pain Management: Stepped Analgesic Approach

Mild to Moderate Pain

• Start with acetaminophen 3000-4000 mg/day in divided doses as first-line due to lower adverse effect profile 1, 2
• NSAIDs may be used with extreme caution in older adults; monitor gastrointestinal toxicity, renal function, blood pressure, and drug interactions 1, 2

Moderate to Severe Pain

• Initiate opioids at low doses with gradual titration, using scheduled dosing for continuous pain 1, 2
• Anticipate and manage opioid-related adverse effects: sedation, cognitive impairment, falls, and constipation 1, 2

Prevention of Postherpetic Neuralgia

Early Neuropathic Pain Agents

• Initiate gabapentin during the acute phase starting at 100-300 mg at bedtime, titrating to 300-600 mg three times daily as tolerated 1, 2
• Nortriptyline 10-25 mg at bedtime with slow titration is preferred over amitriptyline in older adults due to lower anticholinergic burden 1, 2

Topical Therapies

• Lidocaine 5% patches (up to 3 patches for 12 hours daily) provide safe, non-systemic pain relief with no documented systemic absorption or toxicity 1, 2
• The 5% prescription strength is preferred over 4% over-the-counter formulation for optimal efficacy 1
• Particularly valuable for patients with renal impairment or polypharmacy due to minimal drug interactions 1
• Capsaicin may benefit a small proportion of patients but is often poorly tolerated 1, 4

Medications to Avoid in Older Adults

• Avoid muscle relaxants (cyclobenzaprine, carisoprodol) due to significant anticholinergic effects and increased fall risk 1, 2
• Avoid benzodiazepines due to sedation, cognitive impairment, and increased fall risk 1, 2

Vaccination for Prevention

Recombinant Zoster Vaccine (Shingrix) - Preferred

• The recombinant zoster vaccine (RZV/Shingrix) is strongly recommended for all adults ≥50 years with 97.2% efficacy in preventing shingles 3, 1, 2
• Efficacy remains 91% in adults ≥70 years and 89% against postherpetic neuralgia, with protection persisting >83% for up to 8 years 2
• RZV is preferred over live attenuated vaccine (ZVL/Zostavax) due to superior efficacy (97% vs 70%) and safety in immunocompromised patients 3, 5
• Administer as a 2-dose series, with the second dose given 2-6 months after the first (minimum 4-week interval if necessary) 5
• Vaccination is recommended even for individuals with prior herpes zoster 2, 6

Special Populations

• RZV is recommended for adults ≥18 years who are or will be at increased risk due to immunodeficiency or immunosuppression 3
• For patients with history of herpetic keratitis, administer Shingrix (not Zostavax) when keratitis is completely quiescent for at least 2-3 months 5
• RZV contains only viral protein fragment (glycoprotein E) with adjuvant, reducing theoretical risk of viral reactivation compared to live vaccine 5

High-Risk Populations Requiring Heightened Vigilance

• Increased risk observed in patients with diabetes mellitus (RR 1.52), rheumatoid arthritis (RR 1.51), systemic lupus erythematosus (RR 2.08-2.12), lymphoma/leukemia (RR 1.91), HIV/AIDS (RR 1.53), and recent COVID-19 infection 3
• Immunocompromised patients have higher mortality rates, atypical presentations, and greater risk for complications and recurrence 6

Critical Timing Considerations

• The 72-hour window for antiviral initiation is crucial for optimal reduction in disease severity and complications 3, 1, 2, 7, 6
• Early initiation of gabapentin or nortriptyline during acute phase reduces risk of postherpetic neuralgia 1, 2, 4