Patients present varying pharmacodynamics and pharmacokinetics, so achieving this goal with immunosuppressant therapy monitoring can be challenging.
Early on, clinicians used analytical techniques to measure drug concentrations in biological fluids during drug treatment. However, the emergence of therapeutic drug monitoring (TDM) offered an opportunity to minimize the pharmacokinetic component of variability by managing drug therapy using concentrations in the body instead of dosages.
That’s why TDM is used before administering immunosuppressants. Drug concentrations in immunosuppressants can cause adverse effects on transplant patients.
Supratherapeutic drug concentrations, for example, put the patient at-risk of over-immunosuppression which leads to infection. Subtherapeutic drug concentrations can cause the recipient’s body to reject an allograft. This interindividual variability in drug concentrations creates the need for TDM.
Factors that cause interindividual variability include:
Immunosuppressants that need TDM include:
The patients display significant associations between high concentrations with nephrotoxicity and low tacrolimus concentrations with rejection. That makes routine TDM of whole blood concentration critical.
Just a few decades ago, conventional techniques such as venous blood sampling were used to obtain plasma or serum samples for TDM. With the invention of dried blood sampling, clinicians can enjoy a simple and convenient sampling method.
DBS (dried blood spot) sampling involves taking blood samples with a small finger prick using an automatic lancet. With the right setup, the right equipment, and adequate training, this can allow remote patient monitoring.
Mitra microsampling devices are the most convenient system for self-administered blood sampling for immunosuppressant monitoring.