Dried blood spot analysis; facing new challenges

Abstract

Over the last decade, DBS analysis has gained popularity for TDM because it’s a patient friendly sampling proce- dure [1-4]. Additional advantages are prolonged sample stability, lower risk of infections and transportation at ambient temperature [1-3,5]. These advantages may fa- cilitate implementation of TDM in different clinical set- tings including resource limited areas. Patients will bene- fit from DBS analysis but the analytical development and validation of DBS methods is more complex compared to plasma or serum analysis. Additional validation parameters, like the effect of the hematocrit (HT) and blood spot volume need to be eval- uated. Drug substances may also interact with the blood matrix or with the DBS card, resulting in matrix related recovery effects. Unfortunately, official guidelines for val- idation of DBS are not available yet. However, in recent literature, several interesting issues related to analytical DBS research have been discussed [1,6-12]. Ongoing re- search and improved understanding of the factors that influence DBS analysis results will ultimately result in well-founded guidelines for DBS analytical method val- idation. This would be very helpful for daily practice but would also benefit patient safety because uniformity in method validation prevents potential pitfalls during val- idation or method development and increase credibility of assay results. Our aim is to discuss some relevant topics related to DBS development prior to development of future guidelines on DBS development and validation.