Acyclovir concentrations in human breast milk after valaciclovir administration

Jeanne S. Sheffield, Douglas N. Fish, Lisa M. Hollier, Sabrina Cadematori, Brenda J. Nobles, George D. Wendel

Research output: Contribution to journalArticle

19 Scopus citations


OBJECTIVE: The purpose of this study was to determine the valaciclovir and acyclovir pharmacokinetic profiles in serum and breast milk after valaciclovir administration to women after delivery. STUDY DESIGN: Valaciclovir (500 mg twice daily for 7 days) was given to 5 women after delivery who were breast-feeding healthy term infants. Matched serum and breast milk samples were obtained after the initial dose, on day 5 and 24 hours after the drug was discontinued. Infant urine was obtained on day 5. RESULTS: Valaciclovir was rapidly converted to acyclovir. The peak serum acyclovir concentration occurred 3 hours before the peak breast milk concentration (2.7 μg/mL at 1 hour vs 4.2 μg/mL at 4 hours). The serum acyclovir elimination half-life was 2.3 hours. The ratio of breast milk to serum acyclovir concentration was highest 4 hours after the initial dose at 3.4 and reached steady state ratio at 1.85. The median infant urine acyclovir concentration at steady state was 0.74 μg/mL. CONCLUSION: Valaciclovir is rapidly converted to acyclovir and concentrates in breast milk. However, the amount of acyclovir in breast milk after valaciclovir administration is considerably less (2%) than that used in therapeutic dosing of neonates.

Original languageEnglish (US)
Pages (from-to)100-102
Number of pages3
JournalAmerican journal of obstetrics and gynecology
Issue number1
StatePublished - Jan 1 2002


  • Acyclovir
  • Breast milk
  • Herpes simplex virus
  • Valaciclovir

ASJC Scopus subject areas

  • Obstetrics and Gynecology

Fingerprint Dive into the research topics of 'Acyclovir concentrations in human breast milk after valaciclovir administration'. Together they form a unique fingerprint.

  • Cite this

    Sheffield, J. S., Fish, D. N., Hollier, L. M., Cadematori, S., Nobles, B. J., & Wendel, G. D. (2002). Acyclovir concentrations in human breast milk after valaciclovir administration. American journal of obstetrics and gynecology, 186(1), 100-102.