Validated ICP-MS method for measurement of plasma and intracellular antimony concentrations applied to pharmacokinetics of meglumine antimoniate

Abstract

ABSTRACTAimA high-throughput method using inductively coupled plasma mass spectrometry (ICP-MS) was developed and validated for the quantitative analysis of antimony in human plasma and peripheral blood mononuclear cells (PBMCs) from patients with cutaneous leishmaniasis undergoing treatment with meglumine antimoniate.MethodsFor this study, antimony was digested in clinical samples with 1% TMAH / 1% EDTA and indium was used as internal standard. Calibration curves for antimony, over the range of 25 to 10000 ng/mL were fitted to a linear model using a weighting of 1/concentration2. Accuracy, precision and stability were evaluated.ResultsTaking the lower limit of quantitation (LLOQ) to be the lowest validation concentration with precision and accuracy within 20% (25% at the LLOQ), the current assay was successfully validated from 25 to 10000 ng/mL for antimony in human plasma and PBMCs. Dilution studies demonstrated that concentrations up to 100000 ng/mL of antimony in plasma were reliably analyzed when diluted into the calibration range.ConclusionThis protocol will serve as a baseline for future analytical designs, aiming to provide a reference method to allow inter-study comparisons.What is already known about this subjectAntimonial drugs are the mainstay treatment for cutaneous leishmaniasis of which systemically administered pentavalent antimonials (SbV) are widely used, however the pharmacokinetics (PK) of these drugs at the site of action is unknown.A wide range of analytical strategies have been used to quantify antimony in biological samples and atomic absorption spectroscopy is the most employed technique, however, no standardized methods for determination of intracellular concentrations of antimony were available.Relationships between plasma and intracellular drug concentrations remain unknown for most antiparasitic drugs, and PK studies rely on plasma drug concentrations assuming these act as surrogates of intracellular concentrations.What this study addsWe have developed and validated a reproducible and accurate ICP-MS method for the quantification of total antimony in human plasma and peripheral blood mononuclear cells (PBMCs) in accordance with the European Bioanalysis Forum (EBF) recommendations.This method was successfully used to compare pharmacokinetic curves of antimony in plasma and intracellular compartments, in samples collected from patients undergoing treatment for cutaneous leishmaniasis with meglumine antimoniate.