Microsampling in toxicology studies - maximising the scientific, business and 3Rs advantages.

Adoption of a blood microsampling technique can reduce or avoid the use of satellite animals (rodents) for toxicokinetics or other purposes in discovery and toxicology studies and provides refinements applicable for both rodents and larger animals. Microsampling can increase the scientific value of data obtained from rodent studies during drug and (agro)chemical development, enabling multiple endpoints to be investigated and compared in an individual animal in the same way as non-rodents. A cross-sector survey was developed to understand the current use of microsampling in toxicology studies, with the aim of identifying the specific studies in which microsampling was employed and the barriers to wider uptake. A high proportion of the survey responses indicated that microsampling was used, however, the extent varied widely. Some organisations use the technique only in non-GLP studies. Microsampling was used most for pharmacokinetics or toxicokinetics, commonly within small molecule and agrochemical toxicity studies, but less frequently within large molecule, cell/gene therapies or industrial chemical studies. A wide variety of barriers to wider use of microsampling were provided, typically around reticence to change from using larger samples, or not wishing to validate another bioanalytical method given the resources and challenges associated with the validation of a new technology. Despite these barriers, some organisations have adopted microsampling routinely across many/all rodent toxicity studies and there are opportunities to further reduce and refine animal use across all sectors by wider adoption of microsampling.