Is Zidovudine safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Zidovudine. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
A study assigned pregnant women to zidovudine alone or highly-active antiretroviral therapy (HAART: zidovudine, lamivudine and nevirapine) to prevent maternal-to-child transmission of HIV infection. After delivery, all infants received one month of zidovudine prophylaxis; some infants were breastfed and others were formula fed. A higher percentage of infants in the HAART-exposed group had neutropenia than those in the unexposed group at 1 month of age (15.9% and 3.7%, respectively). Hematologic toxicity was transient and asymptomatic. From 2 to 6 months postpartum, no differences in hematologic toxicity were seen between breastfed and formula-fed infants. No statistical difference in hepatic toxicity was seen between the breastfed and formula-fed infants.[ 12 ] A study compared the rates of severe anemia in 3 groups of infants who received postpartum prophylaxis with zidovudine for prevention of maternal-to-child transmission of HIV infection. Through 6 months of age, breastfed infants whose mothers received HAART had a higher rate of severe anemia (7.4%) than breastfed infants whose mothers received only zidovudine (5.3%). Formula-fed infants had the lowest rate of severe anemia (2.5%). The anemia generally responded well to iron and multivitamin supplementation, and discontinuation of zidovudine.[ 13 ]
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
Maternal Levels. Six women were given a single oral dose of 200 mg of zidovudine. Milk samples were collected 1, 2, 4 and 6 hours after the dose. The peak milk concentration occurred 1 to 2 hours after the dose in 4 women and occurred 1 hour later in the others. The average peak milk concentration was 857 mcg/L (range 472 to 1043 mcg/L).[ 4 ] Eighteen women who were receiving oral zidovudine 300 mg twice daily as part of a combination antiretroviral regimen had their milk analyzed at either 2 or 5 months postpartum. Milk samples were provided at a median of 4 hours (range 1 to 8.5 hours) after the last dose. The median zidovudine concentration in breastmilk was 207 mcg/L.[ 5 ] Forty women were given postpartum prophylaxis with unstated dosages of lamivudine, nevirapine and zidovudine (or stavudine if the hemoglobin 8 g/dL). Blood and milk samples were collected once during the first 3 days postpartum and once at 7 days postpartum. The median times after a dose that samples were collected were 5.3 hours (range 0 to 99 hours) for the first sample and 6 hours (range 4.3 to 20 hours) for the 7-day sample. Average breastmilk zidovudine concentrations were calculated only for samples that had detectable ( 20 mcg/L) concentrations of zidovudine. The mean breastmilk concentrations were 130 (n = 11) and 150 mcg/L (n = 13), respectively, at the two sampling times, which was equal to the simultaneous maternal serum concentrations.[ 6 ] Fifty-eight mothers who were taking a combination regimen of lamivudine, nevirapine and zidovudine had their serum and breastmilk analyzed for the presence of these drugs. Mothers took zidovudine 200 mg twice daily starting at 34 to 36 weeks postpartum and continuing until 6 months postpartum. Breastmilk was collected within 24 hours after delivery and at 2, 6, 14 and 24 weeks postpartum at variable times after the previous dose. The median breastmilk zidovudine concentration in 35 selected samples across all visits was 9 mcg/L.[ 7 ] Thirty-eigh
Source: NIH LactMed (National Library of Medicine).
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.