Efavirenz use while Breastfeeding
Drugs containing Efavirenz: Atripla, Sustiva
Efavirenz Levels and Effects while Breastfeeding
Summary of Use during Lactation
In the United States and other developed countries, HIV-infected mothers should generally not breastfeed their infants. Published experience with efavirenz during breastfeeding is limited. In countries in which no acceptable, feasible, sustainable and safe replacement feeding is available, World Health Organization guidelines recommend that all women with an HIV infection who are pregnant or breastfeeding should be maintained on antiretroviral therapy for at least the duration of risk for mother-to-child transmission. Mothers should exclusively breastfeed their infants for the first 6 months of life; breastfeeding with complementary feeding should continue through 12 months of life. The first choice regimen for nursing mothers is tenofovir, efavirenz and either lamivudine or emtricitabine. If these drugs are unavailable, alternative regimens include: 1) zidovudine, lamivudine and efavirenz; 2) zidovudine, lamivudine and nevirapine; or 3) tenofovir, nevirapine and either lamivudine or emtricitabine. Exclusively breastfed infants should also receive 6 weeks of prophylaxis with nevirapine.
Maternal Levels. Thirteen mothers who averaged 15.8 weeks (range 6 to 25 weeks) postpartum were treated with efavirenz 600 mg daily plus zidovudine and lamivudine. Milk and plasma samples were taken 3 to 4 hours after the last dose. Skimmed breastmilk efavirenz concentrations averaged 3.5 mg/L (range 1.3 to 7.4 mg/L).
Five mothers who were taking oral efavirenz 600 mg daily as part of an antiretroviral regimen collected mid-feed milk samples at 0.5, 1, 2, 4, 8, 12 and 24 hours after an evening dose at an average of 146 days after delivery. The average peak level of 4.5 mg/L occurred at about 4 hours after the dose and the average trough milk value was 2.5 mg/L.
One hundred thirty-four mothers who were taking efavirenz 600 mg at bedtime as part of their antiretroviral regimen and their infants were studied. In the first part of the study, women were separated into noncarriers, homozygotes and homozygotes for the CYP2B6 516TT gene. Random breastmilk concentrations had median values of 1610, 2370 and 4070 mcg/L in the three groups, respectively. A subset of mothers underwent extensive sampling of plasma and breastmilk sampling. In these mothers the median peak breastmilk levels were 4020 4540 and 8920 mcg/L, respectively. Corresponding trough milk levels were 1120, 1500, and 2480 mcg/L. The authors estimated that the average dosages that infants would receive would be 344 mcg/kg, 379 mcg/kg and 1340 mcg/kg daily in the maternal noncarrier, heterozygous and homozygous groups, respectively.
Women in Malawi received the option B+ regimen for prevention of mother-to-child transmission of HIV consisting of tenofovir, lamivudine and efavirenz between 6 and 8 pm daily. The efavirenz dose was not stated, but was presumably 600 mg daily. Milk samples collected in the morning from 33 women at month 1 postpartum had a median efavirenz concentration of 1.6 mg/L (IQR 0.86 to 2.3 mg/L). Milk samples collected in the morning from 47 women at month 12 postpartum had a median efavirenz concentration of 1.8 mg/L (IQR 1.0 to 4.3 mg/L).
Infant Levels. Thirteen mothers who averaged 15.8 weeks (range 6 to 25 weeks) postpartum were treated with efavirenz 600 mg daily plus lamivudine and zidovudine (n = 12) or stavudine (n = 1). Plasma samples were taken from their breastfed infants 3 to 4 hours after the last dose. Infant plasma concentrations averaged 0.86 mg/L (range 0.4 to 1.5 mg/L). Infant plasma concentrations averaged 13% of maternal plasma concentrations, but there was no statistically significant correlation between them. Average plasma levels were slightly below the plasma level considered effective for suppression of HIV in adults.
Efavirenz was measured in 117 breastfed (90% exclusive) infants whose mothers were taking efavirenz for HIV infection during pregnancy and postpartum. All infants had detectable efavirenz in their plasma samples at 0 (mean 1.7 mg/L), 8 (mean 0.3 mg/L) and 12 (mean 0.3 mg/L) weeks postpartum. All infants had detectable efavirenz in their hair samples at 12 weeks postpartum at a mean concentration of 1.9 mcg/gram of hair (range 0.34 to 11 mcg/gram). The authors interpreted the results to mean that infants receive substantial exposure to efavirenz during breastfeeding.
One hundred thirty-four mothers who were taking efavirenz 600 mg at bedtime as part of their antiretroviral regimen and their infants were studied. In the first part of the study, women were separated into noncarriers, homozygotes and homozygotes for the CYP2B6 516TT gene. Random infant serum concentrations had median values of 124, 164, and 333 mcg/L in the three groups, respectively. A subset of mothers and infants underwent extensive sampling of plasma and breastmilk sampling. In these infants, median plasma levels were 166, 89 and 293 mcg/L at 2 hours after the maternal dose and 134, 86 and 342 mcg/L at 8 hours after the maternal dose, respectively.
Blood samples were taken from 25 breastfed infants of mothers who were receiving option B+ regimen for prevention of mother-to-child transmission of HIV consisting of tenofovir, lamivudine and efavirenz between 6 and 8 pm daily. The efavirenz dose was not stated, but was presumably 600 mg daily. The median morning infant plasma concentration of efavirenz at 6 months of age was 86.4 mcg/L (IQR 0 to 329 mcg/L). The median morning infant plasma concentration of efavirenz at 12 months of age was 0 mcg/L.
Effects in Breastfed Infants
Thirteen mothers nursed their infants while they were taking efavirenz 600 mg daily, lamivudine 150 mg and zidovudine 300 mg daily (n = 12) or stavudine 60 mg daily (n = 1) . No adverse reactions were reported in the infants after 6 months of breastfeeding, none had developed HIV infection and all were developing normally.
An unblinded study in Uganda compared the outcomes of breastfed infants and their HIV-positive mothers who were randomized to receive antiretrovial therapy that was based either on efavirenz 600 mg once daily or lopinavir 400 mg plus ritonavir 100 mg twice daily during breastfeeding. All mothers received lamivudine 150 mg, zidovudine 300 mg twice daily and trimethoprim-sulfamethoxazole once daily. All infants received prophylaxis with either zidovudine for 1 week or nevirapine for 6 weeks, plus trimethoprim-sulfamethoxazole from 6 weeks of age to 6 weeks after weaning. Almost all of the infants were exclusively breastfed until 6 months of age and about 73% were partially breastfed until 12 months of age. There was no statistical difference in hospitalizations or adverse events including anemia, neutropenia or deaths among infants in the two groups.
Effects on Lactation and Breastmilk
Gynecomastia has been reported among men and at least one woman receiving efavirenz therapy. Efavirenz appears to be much more likely to cause gynecomastia than other antiretroviral agents. Gynecomastia is unilateral initially, but can progress to bilateral. Spontaneous resolution usually occurred within one year, even with continuation of the regimen. The relevance of these findings to nursing mothers is not known. The prolactin level in a mother with established lactation may not affect her ability to breastfeed.
1. World Health Organization. HIV and infant feeding: update. 2007. http://whqlibdoc.who.int/publications/2007/9789241595964_eng.pdf
2. World Health Organization. Consolidated guidelines on the use of antiretroviral drugs for treating and preventing HIV infection. Geneva: World Health Organization. 2013. http://www.who.int/hiv/pub/guidelines/arv2013/en
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6. Palombi L, Pirillo MF, Marchei E et al. Concentrations of tenofovir, lamivudine and efavirenz in mothers and children enrolled under the Option B-Plus approach in Malawi. J Antimicrob Chemother. 2016;71:1027-30. PMID: 26679247
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