From the Guidelines
Valacyclovir is recommended for treating herpes simplex virus (HSV) and varicella-zoster virus (VZV) infections, with specific dosing regimens for each condition, as outlined in the guidelines from the CDC, NIH, and HIV Medicine Association of the Infectious Diseases Society of America 1.
Treatment Regimens
- For genital herpes, initial episodes should be treated with valacyclovir 1 gram twice daily for 7-10 days, while recurrent episodes require 500 mg twice daily for 3-5 days.
- Suppressive therapy for frequent outbreaks (more than 6 per year) involves 500-1000 mg once daily.
- For herpes labialis (cold sores), 2 grams twice daily for one day is effective when started at the first symptom.
- Herpes zoster (shingles) requires 1 gram three times daily for 7 days, ideally started within 72 hours of rash onset for maximum effectiveness.
- For chickenpox in adults and children over 2 years, 20 mg/kg (maximum 1 gram) three times daily for 5 days is recommended.
Mechanism of Action and Considerations
Valacyclovir works by converting to acyclovir in the body, which inhibits viral DNA synthesis. It has better oral bioavailability than acyclovir, allowing for less frequent dosing. Patients with renal impairment require dose adjustments, and adequate hydration should be maintained during treatment. Common side effects include headache, nausea, and abdominal pain, but the medication is generally well-tolerated.
Special Considerations
- HIV-infected persons should use latex condoms during every act of sexual intercourse to reduce the risk for exposure to herpes simplex virus (HSV) and to other sexually transmitted pathogens 1.
- Oral acyclovir prophylaxis during late pregnancy is a controversial strategy recommended by some experts to prevent neonatal herpes transmission, but it is not routinely recommended 1.
- For patients who have frequent, severe recurrences of genital HSV disease, acyclovir prophylaxis might be indicated, but no pattern of adverse pregnancy outcomes has been reported after acyclovir exposures 1.
From the FDA Drug Label
2 DOSAGE AND ADMINISTRATION
Valacyclovir tablets, USP may be given without regard to meals. 2. 1 Adult Dosing Recommendations Cold Sores (Herpes Labialis): The recommended dosage of valacyclovir hydrochloride for treatment of cold sores is 2 grams twice daily for 1 day taken 12 hours apart. Genital Herpes: Initial Episode: The recommended dosage of valacyclovir hydrochloride for treatment of initial genital herpes is 1 gram twice daily for 10 days. Recurrent Episodes: The recommended dosage of valacyclovir hydrochloride for treatment of recurrent genital herpes is 500 mg twice daily for 3 days. Suppressive Therapy: The recommended dosage of valacyclovir hydrochloride for chronic suppressive therapy of recurrent genital herpes is 1 gram once daily in patients with normal immune function. Herpes Zoster: The recommended dosage of valacyclovir hydrochloride for treatment of herpes zoster is 1 gram 3 times daily for 7 days
The recommended treatment regimen for Herpes Simplex Virus (HSV) and Varicella-Zoster Virus (VZV) infections using Valcyclovir (valacyclovir) is as follows:
- For cold sores (HSV): 2 grams twice daily for 1 day taken 12 hours apart
- For initial genital herpes (HSV): 1 gram twice daily for 10 days
- For recurrent genital herpes (HSV): 500 mg twice daily for 3 days
- For chronic suppressive therapy of recurrent genital herpes (HSV): 1 gram once daily
- For herpes zoster (VZV): 1 gram 3 times daily for 7 days
- For chickenpox (VZV) in pediatric patients 2 to <18 years of age: 20 mg/kg administered 3 times daily for 5 days, not to exceed 1 gram 3 times daily 2
From the Research
Treatment Regimen for Herpes Simplex Virus (HSV) and Varicella-Zoster Virus (VZV) Infections
The recommended treatment regimen for HSV and VZV infections using Valcyclovir (valacyclovir) is as follows:
- For the treatment of genital herpes, valacyclovir can be administered in a dosage of 500-1000 mg twice daily for 5-10 days 3, 4.
- For the suppression of recurrent episodes of genital herpes, valacyclovir can be administered in a dosage of 500-1000 mg daily 5, 3.
- For the treatment of herpes zoster, valacyclovir can be administered in a dosage of 1000 mg three times daily for 7-14 days 3, 4.
- For the treatment of herpes labialis, valacyclovir can be administered in a dosage of 2000 mg every 12 hours for 1 day 4.
Efficacy and Safety
Valacyclovir has been shown to be effective in reducing the duration of viral shedding, hastening lesion healing, and decreasing lesion-associated pain in patients with genital herpes and herpes zoster 5, 3, 4.
- The efficacy of valacyclovir is comparable to that of aciclovir and famciclovir in the treatment of genital herpes and herpes zoster 3, 4, 6.
- Valacyclovir is generally well-tolerated, with headache being the most commonly reported adverse event 5, 3.
- However, high-dose valacyclovir therapy (8 g/day) has been associated with a potentially fatal thrombotic microangiopathy (TMA)-like syndrome in immunocompromised patients 5.
Comparison with Other Antiviral Agents
Valacyclovir has been compared with other antiviral agents, including aciclovir and famciclovir, in several studies: