Drug-Drug Interaction Between Rifampicin and Albuvirtide: A Phase 1, Randomized, Open-Label Study

Albuvirtide (ABT) is a novel long-acting fusion inhibitor for human immunodeficiency virus type 1 (HIV-1), and may be co-administered with rifampicin (RIF) in patients concurrent with tubercle bacillus and HIV-1. This study was conducted to investigate the pharmacokinetic effect of co-administration of the two drugs. In the study, 24 healthy volunteers were randomized to receive ABT alone or with RIF. Plasma concentrations were measured using liquid chromatography-tandem mass spectrometry for RIF and competitive enzyme-linked immunosorbent assay for ABT. Co-administration with RIF increased the maximum concentration (C_max) of ABT by 6.93%, and the area under the plasma concentration-time curve (AUC) from time 0 to the last quantifiable concentration (AUC_0-t) by 21.31%; the geometric mean ratio values (GMRs) for C_max and AUC_0-t of ABT when co-administered with RIF, relative to administered alone, were 106.93% (90% confidence interval [CI] 97.53%-117.23%) and 121.31% (90% CI 108.68%-135.40%), respectively. Co-administration with ABT decreased the steady-state C_max (C_max,ss) of RIF by 10.19%, and the steady-state AUC from time 0 to 24 h (AUC_{0-24 h,ss}) by 19.93%; the GMRs for C_max,ss and AUC_{0-24 h,ss} of RIF when co-administered with ABT, relative to administered alone, were 89.81% (90% CI, 79.97%-104.79%) and 80.07% (90% CI 75.68%-84.72%), respectively. The time to reach Cmax (Tmax) of both ABT and RIF demonstrated no statistically significant difference, whether administered alone or concurrently. The pharmacokinetics profiles of both RIF and ABT changed to some extent when co-administered, while no clinically significant impact on these two drugs was observed, indicating that ABT and RIF can be used together without necessitating dose adjustments.