Long-term plasma pharmacokinetics of bedaquiline for multidrug- and extensively drug-resistant tuberculosis

SETTING: Bedaquiline (BDQ) has been approved for the treatment of multidrug- and extensively drug-resistant tuberculosis (MDR/XDR-TB). For many patients treatment is prolonged beyond the recommended 6 months. The long-term pharmacokinetics of BDQ have yet to be elucidated. OBJECTIVE: To evaluate plasma concentrations of BDQ during treatment and its elimination after treatment discontinuation. DESIGN: -desmethyl) metabolite were determined using ultra-performance liquid chromatography with tandem mass spectrometry. RESULTS: Thirteen patients were recruited (35 samples): 10 (31 samples) during BDQ treatment and 3 (4 samples) after BDQ discontinuation. The median duration of treatment with BDQ was 11 months (interquartile range [IQR] 8-14). During treatment, the median plasma BDQ concentrations and M2 were respectively 1264 ng/ml (IQR 910-2244) and 252 ng/ml (IQR 134-290). In one patient, BDQ was detected in the plasma 200 days after treatment discontinuation (528 ng/ml). CONCLUSION: BDQ and M2 plasma concentrations were consistent with good drug efficacy/safety profiles, suggesting good treatment adherence with no relevant drug interactions. The long-term plasma detectability of BDQ after treatment discontinuation may raise the spectre of the emergence of resistance.