Bedaquiline exposure in pregnancy and breastfeeding in women with rifampicin-resistant tuberculosis

Aim We aimed to explore the effect of pregnancy on bedaquiline pharmacokinetics and describe bedaquiline exposure in the human milk of mothers treated for rifampicin-resistant TB, where there is no human data available. Methods We performed a longitudinal pharmacokinetic study in pregnant women treated for rifampicin-resistant TB to explore the effect of pregnancy on bedaquiline exposure. Pharmacokinetic sampling was performed at four time-points over six hours in the third trimester, and again at approximately six weeks postpartum. We obtained serial human milk samples from breastfeeding mothers, and a single plasma sample taken from breastfed and non-breastfed infants to assess bedaquiline exposure. We used liquid chromatography-tandem mass spectrometry to perform the human milk and plasma bedaquiline assays, and population pharmacokinetic modelling to interpret the bedaquiline concentrations. Results We recruited 13 women, six of whom completed the ante- and post-partum PK sampling. All participants were HIV-positive on antiretroviral therapy. We observed lower ante- and post-partum bedaquiline exposures than reported in non-pregnant controls. Bedaquiline concentrations in human milk were higher than maternal plasma (milk to maternal plasma ratio: 24:1). A single random plasma bedaquiline and M2 concentration was available in four infants (median age: 6.5 weeks): concentrations in the one breastfed infant were similar to maternal plasma concentrations; concentrations in the three non-breastfed infants were detectable but lower than maternal plasma concentrations. Conclusion We report low exposure of bedaquiline in pregnant women treated for rifampicin-resistant TB. Bedaquiline significantly accumulates in human milk; breastfed infants receive mg/kg doses of bedaquiline equivalent to maternal doses.