What are the alternatives to Acyclovir (antiviral medication)?

From the Guidelines

Foscarnet is the most effective alternative to acyclovir for treating acyclovir-resistant genital herpes, administered at 40 mg/kg body weight IV every 8 hours until clinical resolution is attained. When considering alternatives to acyclovir, it's crucial to assess the resistance pattern of the HSV strain, as most acyclovir-resistant strains are also resistant to valacyclovir and famciclovir 1. In such cases, foscarnet emerges as a viable option. The treatment regimen for foscarnet involves intravenous administration, which may require hospitalization or close monitoring due to potential side effects. Key points to consider when choosing an alternative to acyclovir include:

• The severity of the infection and the patient's immune status
• The potential for resistance to other antiviral medications
• The need for intravenous versus oral or topical treatment
• The patient's ability to adhere to the prescribed treatment regimen
• Potential side effects and the need for monitoring, such as nephrotoxicity with foscarnet 1. In addition to foscarnet, topical cidofovir gel 1% applied to the lesions once daily for 5 consecutive days may also be effective for treating acyclovir-resistant genital herpes 1. However, foscarnet remains the preferred choice due to its established efficacy in this context.

From the FDA Drug Label

Valacyclovir hydrochloride is the hydrochloride salt of the L‑valyl ester of the antiviral drug acyclovir. The answer is valacyclovir, as it is a prodrug that is converted to acyclovir in the body, making it an alternative to acyclovir 2.

• Key points:
  • Valacyclovir is an antiviral drug that is converted to acyclovir.
  • Acyclovir has antiviral activity against HSV types 1 and 2 and VZV.
  • Valacyclovir is an alternative to acyclovir due to its conversion to acyclovir in the body 2.

From the Research

Alternative to Acyclovir

• Alternative treatments for acyclovir-resistant herpes simplex virus (HSV) infections include:
  • Foscarnet: an antiviral drug that can be used to treat HSV infections that are resistant to acyclovir 3, 4, 5, 6
  • Cidofovir: an antiviral drug that can be used to treat HSV infections that are resistant to acyclovir 3, 4, 5, 6
  • Trifluorothymidine (TFT): a topical antiviral drug that can be used to treat mucocutaneous HSV infections 3, 4
  • Vidarabine: an antiviral drug that can be used to treat HSV infections that are resistant to acyclovir, although it is typically reserved for situations where other therapies have failed 3
  • Pritelivir: an experimental antiviral drug that is currently in clinical trials for the treatment of acyclovir-resistant HSV infections 6

Treatment Protocols

• The treatment protocol for acyclovir-resistant HSV infections may involve:
  • Initiating treatment with foscarnet or cidofovir for disseminated, ophthalmologic, central nervous system, or visceral disease 6
  • Using topical therapy, such as TFT, for mucocutaneous disease 3, 4
  • Considering experimental therapies, such as pritelivir, for patients who do not respond to other treatments 6

Patient Populations

• Immunocompromised patients are at higher risk for developing acyclovir-resistant HSV infections 3, 4, 5, 6
• Patients with allogeneic bone marrow transplants are at particularly high risk for developing acyclovir-resistant HSV infections 5