A quick UPLC–MS/MS method for therapeutic drug monitoring of abiraterone and delta(4)‐abiraterone in human plasma

A Novel LC-MS Method for the Determination of Abiraterone in Rat Plasma and its Application to Pharmacokinetic Studies

Background:

High-Performance Liquid Chromatography (HPLC)-Ultraviolet (UV) and Liquid Chromatography (LC)-Mass Spectrometry (MS)/MS methods have been used to analyse abiraterone (ART); however, a single-quadrupole mass spectrometer with LC-MS systems has never been used to analyse ART.

Objective:

The study aimed to establish a novel, simple assay of quantitating ART in rat plasma through LC-MS.

Method:

The analytical procedure involved the extraction of ART and D4-ART (internal standard, IS) from rat plasma through simple protein precipitation. Chromatographic separation was achieved using an isocratic mobile phase (acetonitrile: 5 mM ammonium formate with 0.1% formic acid, 50:50 v/v) at a flow rate of 0.30 mL/min on a Waters XBridge® C18 column with a total run time of 5 min. LC-MS ion transitions monitored were 350.1 and 354.1 for ART and IS, respectively. The method was validated, and the results met acceptance criteria.

Results:

The lower limit of quantitation achieved was 1 ng/mL, and linearity was 1-8000 ng/mL. The intra- and inter-day precisions were 1.26%-14.20% and 5.49%-13.08%, respectively, in rat plasma.

Conclusion:

LC-MS offers a novel, specific, sensitive, and accurate method for quantifying ART and it was successfully applied to pharmacokinetic studies of ART in rats.

Evaluation of dried blood spots as an alternative matrix for therapeutic drug monitoring of abiraterone and delta(4)-abiraterone in prostate cancer patients

Therapeutic drug monitoring (TDM) approaches may benefit patients treated with abiraterone acetate (AA) as drug efficacy is imprecise and important pharmacokinetic variability is known. Current methods based on the analysis of plasma present the disadvantage of the fast degradation of the analytes in the liquid sample. Dried blood spots (DBS) consist of a minimally invasive and unexplored sampling strategy to monitor the levels of abiraterone (ABI) and delta(4)-abiraterone (D4A) in patients. This study presents the development and validation of a precise and accurate method to monitor ABI and D4A in DBS samples by UPLC-MS/MS. Bioanalytical method validation was carried out according to current guidelines, evaluating the impact of DBS-specific parameters such as hematocrit and spot volume on accuracy. Based on the analysis of quality control samples prepared at low, medium and high concentrations, the method was precise with CV ≤ 6.97 % and 10.26 % for ABI and D4A, respectively. The method was also highly accurate, between 93.6-106.8 % for ABI and 96.0-108.5 % for D4A. The DBS method is compatible with the analysis of samples of unknown volume and hematocrit range of the studied population. In addition, ABI and D4A were stable for 7 days in DBS at room temperature, which is feasible for sample transportation in postal service and analysis in the laboratory. Method application to 16 clinical samples revealed good correlation between measured plasma concentrations and estimated plasma concentrations for ABI (r = 0.884, P < 0.05) and D4A (r = 0.920, P < 0.05). Passing-Bablok regression analysis and Bland-Altmann plots indicated correlation between the results obtained from DBS and plasma, with a slight overestimation of the concentrations of ABI in DBS, which could be related to the small study cohort. Therefore, the results of this first work indicate that DBS consist of a promising alternative sampling strategy in TDM studies of AA.