Therapeutic Drug Monitoring of Immunosuppressants: The Revolution of Microsampling

Therapeutic Drug Monitoring (TDM) is pivotal after tissue or organ transplantation, especially with the intricacies of immunosuppressants (ISPs). Traditional methods, which utilize whole blood specimens, unfortunately, have shortcomings, like weaker correlation with drug concentrations and the invasiveness of drawing wet blood samples.

Evolution of Sampling Methods

While the medical community realized the drawbacks of wet samples, innovations brought forth capillary blood microsampling. Instead of requiring large volumes of blood, only a finger-stick is needed. The drawn blood then dries and is analyzed in labs through advanced methods such as LC-MS/MS. Though effective, this method has its challenges, notably the matrix effect that can skew results.

Alternative TDM methods surfaced, including the use of oral fluids, but they too had their pitfalls. Issues like contamination became major roadblocks.

Dried blood spot (DBS) sampling emerged as a promising alternative. However, its efficacy was diminished by factors like the hematocrit effect.

The Dawn of Volumetric Microsampling

The latest in this evolution is volumetric microsampling, specifically "volumetric absorptive microsampling." Unlike prior methods, hematocrit effects don’t hinder its performance. Devices designed for this method ensure a consistent blood volume regardless of hematocrit.

The Mitra® device with VAMS® technology stands out. It rapidly absorbs the precise blood volume, which can then be sent to labs for detailed analysis.

The hemaPEN® offers another approach, integrating capillary blood and DBS sampling. It takes four identical samples from one finger-stick, ensuring consistent volume and secure storage.

Microsampling devices like Mitra are game-changers. Patients can self-collect samples from the comfort of their homes, sending them to labs without frequent clinic visits. 

Microsampling: A New Age in TDM

The rise of microsampling-based TDM offers more accurate ISP monitoring and presents clear advantages over traditional methods. Notably, for patients who are bedridden or in remote locations, home sampling is a boon.

However, a word of caution to medical professionals: Proper patient training is essential for optimal remote sampling. And post-collection, correct handling and storage are critical for accurate results. To aid in this, the Neoteryx team at Trajan Scientific and Medical offers a plethora of resources and support.

Visit our Resources tab to find the instructions, videos and other resources you need for Mitra devices and hemaPEN devices. 

To get your initial questions about microsampling answered, please visit our Frequently Asked Questions.

For case studies and peer-reviewed publications and other resources, please visit our Technical Resource Library.

Image credits: Trajan, Neoteryx, iStock