The Advantages of Microsampling
Safety Assessment
Tim Sangster

The Advantages of Microsampling

Five things you may not realize about the value of microsampling in research.

Microsampling has become one of the big discussion points over the last few years in animal research. Initially fueled by the Dried Blood Spot (DBS), the conversation has since moved beyond this arena to encompass other techniques and the main focus has landed specifically on liquid microsampling.

Many people are now discussing, investigating and increasingly utilising the benefits that can come by using liquid microsampling in drug development. But we still have a long way to go before microsampling becomes routine. One of the most important thing we, as a field, can do is share our experiences, data and opinions. (My Feb. 24 talk at the Applied Pharmaceutical Analysis-India Conference in Mumbai also focuses on microsampling.)

Here are five top points based on my experience that researchers, companies and project teams may not know or may not have considered with respect to liquid microsampling.

  • It Supports the 3Rs and Saves Money. Microsampling can dramatically improve your toxicology studies and reduce the cost! A modified study design using microsampling for Toxicokinetics (TK) can dramatically reduce the number of animals required, and hopefully remove the TK Satellite groups entirely, thus decreasing the cost of the study. And with fewer animals in the study, you need less test compound, resulting in further savings.
  • It's Not a Paradigm Shift. The idea of moving to microsampling has been viewed as a paradigm shift in the work flows but for many companies bioanalytical assay sensitivity for TK has dramatically improved over the last 10 years for both LC-MS/MS and ELISA based techniques. In my experience a standard assay to support a toxicology study would use 10 µL of sample matrix and a microsampling assay would use 2 µL of sample matrix with minimal loss of analytical sensitivity.
  • One Size Does NOT Fit All. There are times microsampling is not appropriate and these instances are normally involving local exposure studies, typically where dermal or inhalation toxicology is being investigated. If you generate no systemic exposure the use of microsampling, could make it challenging to say that everything possible had been done to generate appropriate exposure data. But in the majority of all other cases, microsampling will be perfectly suitable.
  • Plasma is Plasma. The discussions we have had with regulators is that a blood sample is a blood sample and there are no defined expectations or criteria for the volume collected. Therefore as long as the appropriate scientific steps are taken to demonstrate the assay is appropriate for use following the appropriate bioanalytical guidance for industry, then there are no expected issues with the use of liquid microsampling.
  • Ease of Implementation. Our technicians prefer to use a capillary microsampling approach compared to a standard bleed. The introduction of the capillary microsampling approach at Charles River in the past three years has been very positive among the technical staff. We have also investigated the use of microvettes and dried blood spot to facilitate microsampling, and have focused on the use of capillaries due to the flexibility or sample volume (we have separated as low as 6 µl of blood to plasma), the availability of materials (everything is a relatively standard laboratory consumable) and the ease of acceptance of a liquid sample matrix.