Is Tenofovir Alafenamide safe while breastfeeding?

Effects on the breastfed infant

Numerous studies have demonstrated the safety of tenofovir disoproxil fumarate for breastfed infants.[ 16 - 27 ] See the LactMed record on tenofovir disoproxil fumarate for more information. An open-label, controlled, multicenter phase 3 trial women who were confirmed HIV-positive were randomized to receive one of 3 regimens: dolutegravir, emtricitabine, and tenofovir alafenamide (n = 208); dolutegravir, emtricitabine, and tenofovir disoproxil fumarate (n = 202); or efavirenz, emtricitabine, and tenofovir disoproxil fumarate (n = 207). The regimens were started at 14 to 28 weeks of pregnancy and continued postpartum. Of the 617 liveborn infants, 99% were breastfeeding at time of last infant HIV test, which was as late as 50 weeks of age. The mean infant duration on the study was 47.6 weeks of age. Infants who had any clinical or laboratory adverse event of grade 3 or higher ranged from 25 to 31%, but was not statistically significant between groups. Dolutegravir-containing regimens resulted in lower rates of virological failure, HIV drug resistance, and infant mortality up to 50 weeks postpartum compared with efavirenz, emtricitabine, and tenofovir disoproxil fumarate.[ 28 ]

Effects on milk supply

No information is available on tenofovir alafenamide, but some studies on tenofovir disoproxil fumarate found that mothers breastfed at lower rates when taking antiviral combination therapies that included tenofovir disoproxil fumarate. See tenofovir disoproxil fumarate .

Levels in milk

Tenofovir has poor bioavailability. The more bioavailable tenofovir alafenamide enters cells before releasing tenofovir. Tenofovir is metabolized intracellularly to the active metabolite tenofovir diphosphate. The bioavailability of tenofovir and tenofovir diphosphate from breastmilk are not known, but presumed to be extremely low. Maternal Levels. Fifty-two pregnant women with hepatitis B were given either tenofovir alfenamide (n = 26) or tenofovir disoproxil fumarate (n = 26) from 28 weeks of pregnancy to delivery to prevent mother-to-child transmission. Dosages were not stated. Milk samples obtained 6 hours after delivery from the women taking tenofovir alfenamide contained no detectable ( 0.5 mcg/L) tenofovir. Milk samples obtained 6 hours after delivery from the women taking tenofovir disoproxil fumarate contained a median of 12.83 (IQR 7.46 29.46) mcg/L of tenofovir.[ 10 ] Thirty-six lactating women with hepatitis B were given tenofovir alfenamide 25 mg once a day with food and another 36 were given 300 mg of tenofovir disoproxil fumarate once a day. Breast milk samples from both groups were collected at 48 hours postpartum, but the time with respect to doses was not reported. Tenofovir measured by mass spectrometry was undetectable (lower limit of assay not specified) in breastmilk in all of the women given tenofovir alfenamide, while only 4 of the women who received tenofovir disoproxil fumarate had undetectable tenofovir levels. The average milk tenofovir levels in the remaining 32 mothers was 19.2 mcg/L.[ 11 ] Women with hepatitis B received either tenofovir alfenamide 25 mg (n = 12) or tenofovir disoproxil fumarate 300 mg (n = 4) daily from 24 to 28 weeks of gestation until the 4th week postpartum. Milk samples were collected before the dose and 1, 2, 4, 6, 8 hours after the dose on the 3rd day postpartum. Trough and 1-hour post-dose milk samples were also collected on days 15 and 30 postpartum in mothers who received tenofovir alfenamide. Mothers who rec

Alternatives LactMed lists

• Lamivudine