At IADTMCT 2018 in Brisbane, a must-attend conference of leading lights in the field of Therapeutic Drug Monitoring (TDM), important new work was introduced on the subject of microsampling in TDM. The research was carried out by Dr. Phillip Morgan in the course of routine drug monitoring to test a Volumetric Absorptive Microsampling device in measuring Tacrolimus.
Characteristics of Tacrolimus
- A calcineurin inhibitor (CNI) drug is immunosuppressive
- It has serious aftereffects
- Highly variable in pharmacokinetic
- The requirements for concentration change with time
In all cases of Immunosuppressant Therapy (IST), frequent monitoring is required. As it stands, typical monitoring involves calling the patient to a clinic where they undergo venipuncture. The sample is then taken to the laboratory. The patient may be recalled if the sample is inappropriate.
Alternatively, dried blood samples can be a better way to do the testing. Historically, these have been collected using Dried Blood Spot (DBS) cards or filter paper.
Advantages of DBS
- No venipuncture
- Home sampling is possible
- You can access the results before attending to the clinic
- The methods have been validated
- The drug is stable with no biohazard jeopardy
Limitations of DBS
- Variability in the sample volume
- The effects of chromatography in the paper matrix
- Haematocrit biases may exist
- There may be difficulties in the analytical process
- The properties of the paper matrix may be inconsistent
With the Mitra® device, powered by Volumetric Absorptive Microsampling technology (VAMS™), the game is changed.
- There is no waste in the sampling since a fixed sample is taken.
- The process does not have hematocrit biases.
- There are reproducible properties in the process.
- The sampling process is quantitative.
In the research, routine sampling for Tacrolimus done was performed by absorbing the samples into Mitra tips. A comparison was made between the results and the PPT method. The outcomes of this evaluation were established. Measuring Tacrolimus from VAMS is a precise, simple, fast and accurate process.
From the results of the above test, VAMS is relevant in Tacrolimus monitoring because:
- There is the stability of Tacrolimus on VAMS tip.
- There is the absence of interference, batch variability and hematocrit effect making the results reproducible.
- This process has the potential to make better the patient care.
Remote patient monitoring through microsampling is a new solution for Therapeutic Drug Monitoring that is rapidly gaining traction, as seen in monitoring tacrolimus.