Prediction of Rifampin Exposure using a Single Concentration-time Point in Patients with Tuberculosis

Background: Rifampin exhibits highly variable exposure in tuberculosis patients, leading to adverse effects or treatment failure.This study aimed to develop therapeutic drug monitoring (TDM) strategy for rifampin using a single concentration-time point to estimate the area under the concentration-time curve (AUC), with the potential to reduce the number of blood draws.Methods: Plasma concentration(Cp)-time data were obtained from tuberculosis patients by collecting serial venous blood samples after rifampin administration.The Cp timepoint (C t ) that predicts AUC best was explored using linear regression (Exploration).The accuracy and precision were evaluated using Bland-Altman plot.Physiologically based pharmacokinetic modeling approach was used to evaluate whether the single C t point identified in Exploration provides the best prediction of the AUC (Complement).Results: Cp-time data obtained from 26 participants were evaluable for the determination of AUC by C t .In Exploration, C 4 best predicted the AUC (r 2 =0.91, p<0.0001), followed by C 2 (r 2 =0.84, p<0.0001).In AUC prediction by C 4 , the datapoints for predicted and observed AUC pairs were randomly scattered in Bland-Altman plot with the mean bias of -0.029 g h/mL, and the 95% limit of agreement of -21.1 to 21.1 g h/mL.In Complement, C 4,sim best predicted the AUC (r 2 =0.86, p<0.0001), which supports that C 4 reliably predicted AUC.Conclusions: For improving treatment outcomes in the treatment of tuberculosis, a single concentration monitoring is applicable to rifampin TDM instead of AUC, potentially making the process less invasive, painful and cumbersome for patients, clinicians and healthcare providers.