What antivirals (antiviral medications) are recommended for the treatment of shingles?

Antiviral Medications for Shingles (Herpes Zoster)

Three oral antiviral medications are recommended for the treatment of shingles: acyclovir, valacyclovir, and famciclovir. These medications are most effective when started within 72 hours of rash onset and help reduce the duration of symptoms, accelerate healing, and may decrease the risk of postherpetic neuralgia.

First-Line Antiviral Options

• Famciclovir: 500 mg three times daily for 7 days 1, 2
• Valacyclovir: 1000 mg three times daily for 7 days 3, 4
• Acyclovir: 800 mg five times daily for 7 days 5, 6

Comparative Efficacy

• Valacyclovir and famciclovir have better oral bioavailability than acyclovir, requiring less frequent dosing and potentially improving adherence 4, 7
• Valacyclovir has been shown to alleviate zoster-associated pain and postherpetic neuralgia significantly faster than acyclovir in comparative studies 4
• Famciclovir recipients experienced resolution of postherpetic neuralgia twice as fast as those receiving placebo, with a 3.5-month reduction in median duration for patients 50 years or older 2
• Preliminary results indicate that valacyclovir 1000 mg three times daily and famciclovir 500 mg three times daily have similar efficacy in speeding resolution of acute herpes zoster rash and shortening the duration of postherpetic neuralgia 4

Alternative Dosing Regimens

• Valacyclovir 1.5 g twice daily for 7 days has been shown to be as safe and effective as three-times-daily dosing for uncomplicated herpes zoster in immunocompetent patients, which may improve patient compliance 8
• For persistent or recalcitrant ophthalmic herpes zoster in immunocompetent patients, valacyclovir 1000 mg every 8 hours for 7 days may be considered 3

Special Populations

Immunocompromised Patients

• Higher doses of antiviral therapy are typically required for immunocompromised patients 5
• For HIV-infected patients, acyclovir 400 mg orally three to five times a day is recommended until clinical resolution 5
• Famciclovir is indicated for the treatment of recurrent episodes of orolabial or genital herpes in HIV-infected adults 1
• For severe cases in immunocompromised patients, intravenous acyclovir 5 mg/kg every 8 hours may be required 5

Patients with Renal Impairment

• Valacyclovir should be used with caution in patients with impaired renal clearance, and dosage adjustment is necessary 3

Severe Disease

• For patients with severe disease or complications requiring hospitalization, intravenous acyclovir 5-10 mg/kg body weight every 8 hours for 5-7 days or until clinical resolution is recommended 5, 3

Treatment Considerations

• Antiviral medications are most effective when started within 72 hours after the onset of rash 1, 6
• However, starting treatment later than 72 hours after rash onset may still provide benefit, particularly for reducing zoster-associated pain 4
• Topical antiviral therapy is substantially less effective than systemic therapy and is not recommended 9
• The most common side effects of these antiviral medications include headache and nausea, but they are generally well tolerated 1, 4

Antiviral Resistance

• If lesions persist in a patient receiving acyclovir treatment, resistance should be suspected 5
• All acyclovir-resistant strains are resistant to valacyclovir, and most are resistant to famciclovir 5
• For severe cases caused by proven or suspected acyclovir-resistant strains, foscarnet 40 mg/kg body weight IV every 8 hours until clinical resolution is attained is often effective 5

In conclusion, oral antiviral therapy with acyclovir, valacyclovir, or famciclovir is beneficial for the treatment of shingles, particularly when initiated within 72 hours of rash onset. Valacyclovir and famciclovir offer advantages of less frequent dosing compared to acyclovir, potentially improving patient adherence and treatment outcomes.