What is the recommended use of Valtrex (valacyclovir) in a pregnant patient with Herpes Simplex Virus 2 (HSV 2)?

From the Guidelines

Valacyclovir (Valtrex) is recommended for pregnant patients with HSV-2 to prevent outbreaks and reduce the risk of transmission to the baby during delivery, with suppressive therapy typically started at 36 weeks of gestation at a dose of 500 mg orally twice daily until delivery. This recommendation is based on the most recent evidence from the 2022 study published in Clinical Infectious Diseases 1, which demonstrated that women with a history of genital herpes have decreased risk of viral shedding, recurrences, and cesarean deliveries when suppressive acyclovir or valacyclovir is given starting at 36 weeks’ gestational age.

• For patients experiencing an active outbreak during pregnancy, the recommended treatment is 1 gram orally twice daily for 7-10 days.
• If a woman has her first clinical episode of genital herpes during pregnancy, a higher dose of 1 gram three times daily for 7-10 days may be prescribed.
• Valacyclovir is considered safe during pregnancy (FDA Category B) and works by converting to acyclovir in the body, which inhibits viral DNA replication.
• This suppressive therapy significantly reduces the risk of viral shedding at the time of delivery, decreasing the need for cesarean section.
• Regular monitoring for outbreaks throughout pregnancy is important, and patients should inform their healthcare provider immediately if symptoms develop. The American College of Obstetrics and Gynecology recommends against routine screening for HSV serostatus during pregnancy based on a lack of evidence for cost-effectiveness, as stated in the 2022 study 1. However, it is recommended to screen pregnant women for a history of genital herpes. Although there are some concerns about the safety of HSV antivirals during pregnancy, acyclovir remains category B, and valacyclovir is considered safe during pregnancy 1. An older study from 1998 1 mentioned that the safety of systemic acyclovir and valacyclovir therapy in pregnant women has not been established, but this information is outdated and superseded by more recent evidence.

From the FDA Drug Label

The Valacyclovir Pregnancy Registry documented outcomes of 111 infants and fetuses exposed to valacyclovir during pregnancy (28 with earliest exposure in the first trimester, 31 during the second trimester, and 52 during the third trimester). The occurrence of major birth defects during first-trimester exposure to valacyclovir was 4.5% (95% CI: 0.24% to 24.9%) and during any trimester of exposure was 3.9% (95% CI: 1.3% to 10. 7%).

The recommended use of Valtrex (valacyclovir) in a pregnant patient with Herpes Simplex Virus 2 (HSV 2) is not explicitly stated in the drug label. However, based on the available data from the Valacyclovir Pregnancy Registry, valacyclovir may be used in pregnant women with HSV 2, but the potential risks and benefits should be carefully considered. The drug label notes that available studies have methodological limitations, including insufficient sample size to support conclusions about overall malformation risk or for making comparisons of the frequencies of specific birth defects 2.

From the Research

Valtrex Use in Pregnant Patients with HSV 2

• Valtrex (valacyclovir) is used to reduce recurrent genital herpes in pregnant women, particularly those with a history of HSV 2 infection 3, 4.
• Studies have shown that valacyclovir suppressive therapy, starting at 36 weeks' gestation, can decrease the number of women with subsequent clinical HSV recurrences 3, 4.
• The recommended dosage of valacyclovir for pregnant women with recurrent genital herpes is 500 mg twice daily 3, 4.
• Valacyclovir has been shown to be safe and well-tolerated in pregnant women, with no significant differences in maternal or obstetric complications compared to placebo 3, 4.

Prevention of Neonatal Herpes

• The risk of neonatal herpes is estimated to be between 25% and 44% if a non-primary and primary first genital herpes episode is ongoing at delivery, and 1% for a recurrence 5.
• Antiviral prophylaxis, such as valacyclovir, should be offered to women with either a first or recurrent episode of genital herpes during pregnancy from 36 weeks of gestation until delivery 5, 4.
• Cesarean delivery is recommended if a first episode of genital herpes is suspected or confirmed at the onset of labor, or if it occurred less than 6 weeks before delivery 5.

Comparison with Other Antiviral Medications

• Acyclovir is also effective in suppressing genital herpes simplex virus recurrences in pregnant women, and its administration has been shown to be safe and well-tolerated 6.
• Valacyclovir and acyclovir have similar efficacy and safety profiles, but valacyclovir has a more convenient dosing schedule 7, 6.