out of the waiting room, into the living room: how technology is helping TDM patients get help without leaving home
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 consequently optimized and individualized dosage regimen, enables maintaining the drug’s concentration within a targeted therapeutic range.
Not every drug needs to or can be monitored, and certain criteria need to be met for TDM to be a sound practice:
- Quality drug assay methods – to even consider TDM for a specific drug, accurate, precise, sensitive, and specific drug assay procedures that account for any clinically relevant information, such as dosage regimen, time of sampling, and patient condition, must be in place.
- Drug is used for treatment of life-threatening conditions, where the lack of therapeutic effect is dangerous for the patient (bisoprolol, used for treatment of heart failure), the drug itself has a low therapeutic index and is considered unsafe (paracetamol), or both (theophylline, used for treatment of respiratory diseases such as chronic obstructive pulmonary disease).
- The drug exhibits high intraspecific variability in terms of pharmacokinetics (poor relationship between applied dose and the amount of free drug exerting pharmacological effect) and low intraspecific variability in terms of pharmacodynamics (good relationship between the serum drug concentration (SDC) and pharmacological effect)
How Technological Advancements Help TDM Patients
Just a quick look at the TDM criteria reveals that the sensitive populations that benefit the most from TDM – newborns, elderly, terminally ill patients, individuals with disabling, life-threatening acute conditions - are likely to be the most strained by traditional TDM requirements, especially frequent clinic visits and invasive sampling of large volumes of blood.
With technological advancements in all medical fields, alternative matrices, such as dried microsamples, allow for off-site TDM, providing the most affected patients with a host of benefits:
- Home-based TDM removes the strain of frequent visits to a medical professional
- Robust, non-invasive procedures are suitable for self-sampling while providing relevant clinical data from capillary blood sampling
- Fast, straightforward sampling promotes patient compliance, further aiding in therapy optimization/individualization
Off-site TDM involving remote sampling also facilitates pharmacokinetic studies in critical patient populations for a range of drugs that currently lack this data. 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.