Okay to breastfeed while taking lamivudine or tenofovir: study
By Megan Brooks
Lamivudine and tenofovir disoproxil fumarate (TDF) are safe for breastfeeding women, according to a new review of the evidence.
Although evidence has accumulated on the efficacy and safety of these two drugs against hepatitis B virus (HBV) during pregnancy, their safety during breastfeeding has not been well studied.
The labels on both drugs recommend against their use during breastfeeding, which is a problem since breastfeeding has advantages especially in low-income countries where HBV is highly endemic, the authors note in a report online October 13 in Clinical Infectious Diseases.
"Our review of the existing evidence supports that the current drug labeling against breastfeeding while taking lamivudine and tenofovir DF needs to be reconsidered since the evidence points to lower drug exposure via breastfeeding than in utero. These drugs are not contraindicated in utero," Dr. Chloe L. Thio of Johns Hopkins University in Baltimore told Reuters Health by email.
Lamivudine, a nucleoside analog used to treat HIV as well as chronic HBV, is secreted in breast milk and several studies have looked at lamivudine in breastfed infants.
A study from Malawi of 30 mother-infant pairs showed that the lamivudine concentration in breastfed infants was only 3.7% of the mother's level despite the fact that lamivudine was concentrated in breast milk.
A study from Kenya calculated that the daily dose of lamivudine to infants via breast milk was 2% of that of the recommended dose for treatment for HIV in infants >3 months of age. "Thus, despite the fact that lamivudine is concentrated in the breast milk, it is not as efficiently absorbed by the infant through that route as compared with the transplacental route. This study demonstrates that the infant is exposed to significantly higher amounts of lamivudine in utero than via breast feeding," the authors say.
Tenofovir, a nucleotide analog, is also highly effective against HIV and chronic HBV. "The limited data on tenofovir excretion into breast milk demonstrate that the infants receive low doses of tenofovir via breastfeeding," the authors note.
In one study of five Ivorian women treated with one tablet of nevirapine (200 mg) plus two tablets of TDF (300 mg)-emtricitabine (FTC) (200 mg) at the start of labor and one TDF-FTC tablet daily for seven days postpartum, the median maximal tenofovir concentration in breast milk was 14.1 ng/ml. This amount is lower than in maternal serum or cord blood. "Thus, given the amount of milk ingested by the infant, the median amount of tenofovir ingested would be 0.03% of the recommended neonatal dose," the authors say.
A study from Malawi and Brazil found that levels of tenofovir in breast milk two days after a single 600 mg TDF dose during labor were 6.3-17.8 ng/ml.
"It appears difficult to justify that these drugs can be recommended during pregnancy but contraindicated during breastfeeding," the authors conclude.
"Our review of the existing data suggests that lamivudine and TDF should not be contraindicated during breastfeeding; however, long-term studies of infants breastfed while their mothers were receiving lamivudine or TDF are warranted," they say.
Clin Infect Dis 2014.
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