Is Valacyclovir safe while breastfeeding?

Effects on the breastfed infant

In a study of pregnant women with concurrent HIV and Herpes simplex infections, mothers received zidovudine 300 mg daily from week of pregnancy until 12 months postpartum and nevirapine at delivery. Half of the women (n = 74) also received valacyclovir 500 mg orally twice daily from 34 weeks gestation until 12 months postpartum. At 6 weeks postpartum, all infants who received acyclovir in breastmilk had normal serum creatinine ( 0.83 mg/dL). Their median serum creatinine and alanine aminotransferase (ALT) values, and growth were no different from those of unexposed infants, with the exception of one infant with an ALT level of 70.1 units/L. Infants whose mothers received valacyclovir generally had adverse effects that were similar to the placebo group, except that treated infants had a lower risk of eczema and oral thrush than infants in the placebo arm.[ 3 , 6 ]

Effects on milk supply

Relevant published information was not found as of the revision date.

Levels in milk

Valacyclovir is a prodrug that is rapidly converted to acyclovir in the body. Maternal Levels. Five mothers who were nursing neonates were given valacyclovir 500 mg orally every 12 hours for 5 days. Valacyclovir was not detected in milk. Median peak acyclovir concentrations in milk of 4.2 mg/L occurred at 2 to 4 hours after the first dose and was similar after the last dose. The authors calculated the median milk concentration at steady-state to be 2.24 mg/L. The median half-life in milk was 2.1 hours (range 1.3 to 12.2 hours).[ 5 ] A 500 mg maternal dose of valacyclovir twice daily would provide a breastfed child with a daily oral acyclovir dosage of approximately 0.6 mg/kg. This is about 1% of the neonatal intravenous dose of acyclovir. In a study of pregnant women with concurrent HIV and Herpes simplex infections, mothers received zidovudine 300 mg daily from week of pregnancy until 12 months postpartum and nevirapine at delivery. Half of the women (n = 74) also received valacyclovir 500 mg orally twice daily from 34 weeks gestation until 12 months postpartum. Milk samples (timing not stated) from 44 women obtained at 2 weeks postpartum found detectable acyclovir in 35 samples, with a median concentration of 2.6 mg/L (range 0.15 to 10.15 mg/L) Three of the 9 women with undetectable milk acyclovir levels had missed one or more doses of valacyclovir in the previous 2 days.[ 6 ] Infant Levels. The urine of 5 infants whose mothers were taking valacyclovir 500 mg every 12 hours orally was collected. Valacyclovir was not detected in any of the infant's urine. The median infant urine acyclovir concentration on day 5 of therapy was 0.74 mg/L.[ 5 ]

Alternatives LactMed lists

• Acyclovir