Acyclovir excretion in human breast milk

Anna Taddio, Julia Klein, Gideon Koren

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


OBJECTIVE: To measure acyclovir concentrations in the breast milk of a lactating woman using the drug for herpes zoster while nursing her 7-month-old infant. METHODS: The maternal dosage of acyclovir was 800 mg five times daily for seven days. Three random breast milk samples collected on the fifth and sixth days of therapy were analyzed for acyclovir concentrations with radioimmunoassay (RIA). RESULTS: Acyclovir concentrations in breast milk ranged from 18.5 μmol (4.16 μg/mL) to 25.8 μmol (5.81 μg/mL). An estimate of the infant’s dosage ingested through nursing was 0.73 mg/kg/d, or approximately 1 percent of the maternal dose in milligrams/kilograms/day. The baby was nursed without any signs of adverse effects. CONCLUSIONS: Acyclovir was measured in clinically insignificant concentrations in the milk of a woman receiving large dosages for herpes zoster. Breast feeding continued without adverse effects to the nursing infant.

Original languageEnglish
Pages (from-to)585-587
Number of pages3
JournalAnnals of Pharmacotherapy
Issue number5
StatePublished - May 1994
Externally publishedYes


Dive into the research topics of 'Acyclovir excretion in human breast milk'. Together they form a unique fingerprint.

Cite this