Kang and Lee define TDM (therapeutic drug monitoring) as a clinical laboratory measurement of a particular drug in a patient’s bloodstream that, with proper medical interpretation and optimized and individualized dosage regimen, enables maintaining the drug’s concentration within a targeted therapeutic range. In Europe, TDM programs are getting a boost from remote specimen collection and microsampling technology.
Adult organ transplant patients at Guy's and St Thomas, an NHS Foundation Trust hospital in the UK, and Rennes University Hospital in France, are using remote specimen collection devices to enable their therapeutic drug monitoring to continue while they remain safe at home. After an organ transplant procedures, patients must typically take drugs such as tacrolimus, to prevent ensure organ function and prevent organ rejection.
Dosing of tacrolimus and creatinine must be monitored closely in patients who have received kidney transplants, for example. Previously, these patients had to travel frequently to the hospital for specimen collection and in-person TDM consultations. Pediatric organ transplant patients at Nottingham Children's Hospital in England also are benefitting from a program that provides remote specimen collection kits for at-home TDM.
Thanks to Mitra® devices based on volumetric absorptive microsampling (VAMS®), patients in the UK and Europe can get specimen collection kits from their hospital delivered by mail. They use the kits to self-collect their own specimen samples at home and send them back to their designated lab via regular mail.
The samples are processed and analyzed to determine if the drug levels in each patient's system are optimal. The care team accesses the lab results through a secure digital system, and follows up with patients via phone or a video call to discuss results and any dosing changes.
Not every drug needs to be monitored, and certain criteria need to be met for TDM technology to be a sound practice. Drugs that can and should be monitored, include:
Just a quick look at the TDM criteria reveals that the sensitive populations that benefit the most from TDM – newborns, the elderly, chronically ill, or terminally ill patients, individuals with disabling conditions – are likely to be the most strained by traditional TDM requirements, especially the frequent clinic visits and invasive blood draws that include sampling of large volumes of blood.
These are the very patients who can benefit most from remote technologies and tools that allow them to use minimally invasive self-sampling while safe at home to avoid unnecessary travel and exposure to contagions.
Technological advancements in all medical fields, alternative sampling matrices, such as dried microsamples, allow for many applications of remote TDM, providing the most vulnerable patients with a host of benefits, including:
Off-site TDM involving remote sampling also facilitates pharmacokinetic studies in critical patient populations for a range of drugs that currently lack this data. Remote specimen collection and microsampling can accelerate this effort. With a better understanding of a drug’s pharmacokinetics in particular populations, along with procedures for cytochrome P450 phenotyping, a better understanding of dose-effect relationship will reduce the need for TDM, leading to increased patient care with less strain on the patients themselves.