An article by Binu Susan Mathew et al at the Christian Medical College, Vellore, Tamil Nadu, India and Royal Brisbane and Women’s Hospital, Brisbane, Australia, published in the July-August 2022 edition of Clinical Biochemistry, described a thorough analytical and clinical validation of tacrolimus and creatinine from dried capillary microsamples. The paper is entitled “Analytical and clinical validation of dried blood spot and volumetric absorptive microsampling for measurement of tacrolimus and creatinine after renal transplantation.”
The study compared venous whole blood samples, dried blood samples collected on Mitra® microsampling devices with VAMS® technology, and dried blood spot (DBS) filter cards from 152 transplant patients. The authors concluded that VAMS was the preferred single sampling option for the estimation of tacrolimus and creatinine in renal transplant patients.
Of the transplants conducted in India, the vast majority were renal grafts (9,751). This was just under 10% of the global number of renal grafts (kidney transplants) conducted globally that year. Although there were reported to be 550 transplant centers in India in 2019, there were 29,636 patients that were still waiting for a new kidney.
According to the study paper by BS Mathew et al reviewed here, most of the transplant centers in India are in the bigger cities. However, around 70% of the population (~1 billion) live in rural areas. This means that many organ transplant patients don’t have easy access to transplant centers or therapeutic drug monitoring programs.
The co-authors of the study paper commented that conducting therapeutic drug monitoring (TDM) for transplant patients living in different areas requires transport that offers cold shipping of venous blood samples to maintain temperature control. Yet, cold shipping for blood samples and other biological specimens is expensive as well as hazardous.
For these reasons, the authors stated that collection of capillary blood for TDM of the calcineurin inhibitor tacrolimus and monitoring of the renal function biomarker creatinine, using Mitra devices with VAMS and DBS are an ideal solution to collect samples from people in rural areas. Moreover, a remote specimen collection approach is more convenient and less burdensome for patients. This approach to toxicology studies and therapeutic drug monitoring also allows for remote interactions via telehealth between the physician and the patient for dose adjustments during their post-transplant treatment.
The group thus conducted a study to validate an LC-MS/MS assay using both VAMS dried blood samples and liquid blood samples collected from patients. They concluded that VAMS is the preferred sampling option for masurement of tacrolimus and creatinine in transplant patients. They propose that this approach ensures uninterrupted monitoring of patients at home after renal transplantation and is especially helpful when long distance travel to visit a transplant center for follow-up care is challenging.
This study demonstrated the importance of a thorough analysis and validation of the parameters to allow for creation of predictive formulas to bridge between wet venous collection and capillary dried blood. It must be noted that in this study, sample collection was conducted under very controlled conditions using one phlebotomist to collect all samples. When developing a remote sampling strategy where patients will be self-collecting their samples, it is vital that clear instructions are given to reduce the chance of incorrectly collected samples.
Neoteryx, part of Trajan Scientific and Medical, has developed high-quality training materials and tools to help ensure that remotely collected samples are of the highest quality in order to deliver the highest success in studies. These tools and materials have been used effectively in many previous studies, as evidenced in the literature.
The company has also developed another user-friendly sampling tool called the hemaPEN®. This newer device is designed for easy sampling from any angle. With hemaPEN, it is nearly impossible to under- or over-sample. Once the end-user finishes collecting their samples, they click the device into its plastic base. This action transfers four blood samples of 2.74 µL each into a cartridge of four pre-cut Whatman 903 DBS disks within the device.
This article was summarized for our readers by James Rudge, PhD, Neoteryx Technical Director. This is curated content. To learn more about the important research outlined in this blog, visit the original article in Clinical Biochemistry.
More information about remote microsampling for TDM can be found via our Microsampling for Drug Monitoring page.
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