Quantification of Rifapentine, a Potent Antituberculosis Drug, from Dried Blood Spot Samples Using Liquid Chromatographic-Tandem Mass Spectrometric Analysis

Abstract

The quantification of antituberculosis drug concentrations in multinational trials currently requires the collection of modest blood volumes, centrifugation, aliquoting of plasma, freezing, and keeping samples frozen during shipping. We prospectively enrolled healthy individuals into the Tuberculosis Trials Consortium Study 29B, a phase I dose escalation study of rifapentine, a rifamycin under evaluation in tuberculosis treatment trials. We developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying rifapentine in whole blood on dried blood spots (DBS) to facilitate pharmacokinetic/pharmacodynamic analyses in clinical trials. Paired plasma and whole-blood samples were collected by venipuncture, and whole blood was spotted on Whatman protein saver 903 cards. The methods were optimized for plasma and then validated for DBS. The analytical measuring range for quantification of rifapentine and its metabolite was 50 to 80,000 ng/ml in whole-blood DBS. The analyte was stable on the cards for 11 weeks with a desiccant at room temperature and protected from light. The method concordance for paired plasma and whole-blood DBS samples was determined after correcting for participant hematocrit or population-based estimates of bias from Bland-Altman plots. The application of either correction factor resulted in acceptable correlation between plasma and whole-blood DBS (Passing-Bablok regression corrected for hematocrit; y ‫؍‬ 0.98x ؉ 356). Concentrations of rifapentine may be determined from whole-blood DBS collected via venipuncture after normalization in order to account for the dilutional effects of red blood cells. Additional studies are focused on the application of this methodology to capillary blood collected by finger stick. The simplicity of processing, storage, shipping, and low blood volume makes whole-blood DBS attractive for rifapentine pharmacokinetic evaluations, especially in international and pediatric trials.

Comparative Analysis of Ampicillin Plasma and Dried Blood Spot Pharmacokinetics in Neonates

“…While correlation analysis demonstrated strong association between CONC Plasma and CONC DBS , the bias exceeded >15%, demonstrating that bias was present. 14–16 Bias between plasma and DBS concentrations was expected based on in vitro data suggesting lack of ampicillin penetration into red blood cells. A similar phenomenon was observed with in vivo data as evidenced by the ratio of DBS to plasma concentrations.…”

“…The Bland-Altman plot of the ratio of CONC DBS (and eCONC Plasma ) to CONC Plasma was computed and plotted against mean combined concentrations, together with the 95% confidence interval of the mean ratio. 14 Except for the PK modeling, all analyses were performed using SPSS PASW 22 (SPSS Inc., Chicago, IL, USA).…”

Absolute Quantification of Rifampicin by MALDI Imaging Mass Spectrometry Using Multiple TOF/TOF Events in a Single Laser Shot

“…As RIF and RPT possess similar physical and chemical properties, the use of RPT as an internal standard represents an ideal test case for MALDI MS/MS quantification using multiple TOF/TOF events. 54 Working calibration (3.00-100.0 μM) and QC (50.0 μM) solutions of RIF included 50.0 μM RPT as an internal standard and a final concentration of 30% pooled human plasma containing K2EDTA as an anticoagulant. Each solution was pre-mixed with THAP prior to manual spotting onto a gold-coated stainless steel MALDI target.…”

Translating innovative pharmacokinetic sampling techniques into improved antibiotic dosing regimens in critically ill patients

“…There is considerable interest in applying these techniques to clinical applications such as pharmacokinetic studies [69,70], newborn and infant screening [71,72], microbiological screening [73], forensic and toxicology investigations [74][75][76] and therapeutic drug monitoring [77,78].…”

“…These advantages include: reduced blood volume requirements; simplification of obtaining sample from finger or heel prick rather than cannulae; simplification of sample processing as centrifuges are not required to make plasma; and, reduced costs of sample shipping and storage as samples often do not require freezing and may not be classed as biohazards during shipment [88,94,104]. The DBS technique is being used across a wide range of applications, including pre-clinical pharmacokinetic studies [69,70], new-born and infant screening [71,72], microbiological screening [73], forensic and toxicology investigations [74][75][76] and therapeutic drug monitoring [77,78].…”