Dried blood spot sampling: practical considerations and recommendation for use with preclinical studies.

At present it is necessary to use animals to generate toxicokinetic data as part of preclinical safety studies. However, ethical standards require animal use to be carefully monitored and the principles of the 3Rs: replacement, reduction and refinement, to be considered and applied. Use of dried blood spot (DBS) samples, typically 10 to 20 µl, rather than the larger blood volumes required to obtain plasma samples, fully embraces the latter two principles of reduction and refinement. The use of DBS sampling enables the number of rodents per study to be reduced whilst also refining the way blood samples are taken from both rodents and non-rodents. The recent changes to the European Directive on the protection of animals used for scientific purposes favor DBS sampling becoming the standard for generation of toxicokinetic data, and imply that pharmaceutical companies will have to justify why plasma samples (and therefore larger blood volumes) are required for bioanalysis. Use of DBS samples has been, and is being, discussed widely within the pharmaceutical industry as the move away from taking large blood volumes becomes inevitable.