A validated capillary microsampling liquid chromatography–tandem mass spectrometry method for quantification of antisense oligonucleotides in mouse serum
Yuan L, Dupuis J-F, Vrionis V, Mekhssian K & Magee T | Bioanalysis, 15(12), 683-694, (2023)
Keywords: • antisense oligonucleotides • capillary microsampling • CMS • hybridization • LC-MS/MS • microsampling
Microsampling techniques, which typically collect less than 100 μl of blood, have been gaining increasing interest in drug research and development for the quantification of drugs, their metabolites or endogenous substances in liquid biological samples (e.g., blood, plasma or serum) [1,2]. One major advantage of microsampling is its significantly lower blood sample collection volume compared with conventional methods (for which typically 300 μl of blood is collected at each time point in a rat study). Thus, for studies in small animals (e.g., rats and mice), microsampling is desirable from an ethical perspective, as it can significantly reduce the number of animals and therefore be more compliant with the ‘3Rs’ (reduce, refine and replace). Juvenile animal testing is on the rise for pediatric drug development and, with the strict constraints on sample collection volumes in juvenile animals, microsampling becomes especially attractive. Commensurate with the reduced number of dosed animals, the required amount of total drug will be reduced accordingly, resulting in further cost reductions for studies.
Quantitative bioanalysis of drug candidates is an essential component of drug discovery and development. It provides critical information on the systemic exposure of drug candidates and, therefore, enables the evaluation and understanding of the toxicokinetic (TK) and pharmacokinetic (PK) properties of drug candidates. Commonly used microsampling techniques for quantitative bioanalysis include dried blood spot (DBS) and volumetric absorption microsampling (VAMS) [1,2]. These techniques involve the collection of whole blood samples and storing and using the samples in dried blood form for analysis. DBS and VAMS samples are convenient for sample collection and storage. There have been reliable and robust workflows developed and applied for the bioanalysis of these samples [1–4]. One main concern in using these types of dried blood microsampling techniques is the regulatory acceptance of blood concentration data. Traditionally, plasma or serum samples are used for the quantification of drug concentrations, and the generated plasma/serum drug concentration data are then used to determine PK/TK parameters. The blood concentration data generated from DBS or VAMS samples often need to be converted to plasma concentrations for data interpretation and decision-making [4]. Regulatory agencies recommend conducting correlative studies between DBS microsampling and traditional sampling during drug development to establish their concordance [2,5]. In contrast, capillary microsampling (CMS) is another type of microsampling technique that uses a capillary micropipette to collect a small volume of blood via capillary force [6–11]. The collected blood in capillary tubes can be further processed into plasma or serum for analysis. The plasma/serum collected by CMS is the same matrix as conventional sampling; therefore, there is no need to convert drug concentrations or conduct a bridging study. CMS has been applied to regulated toxicity studies for small-molecule compounds under good laboratory practice (GLP) environments [8,9].
