Breaking the Therapeutic Drug Monitoring Logistics Barrier

Therapeutic drug monitoring (TDM)2 is one of the most complex laboratory testing processes in modern laboratory medicine practice. Based on the simple engineering principle of feedback control, TDM strives to regulate an individual's exposure to a drug by measuring the drug's concentrations, usually at steady state and at distributional equilibrium, and then use these concentrations to determine the drug's new dose. Unlike a thermostat in a home that can measure temperature in real time and trigger the introduction of more heat from a furnace until a target temperature is reached, drug concentration monitoring currently requires multiple steps, including administration of a drug at the correct dose, collection of one or more blood samples at precise times following drug administration, transport of these samples to a laboratory where they can be analyzed, and then returning the concentration results to a physician, who can adjust the future dose. Moreover, the exposure to a drug is often estimated through fitting of sparsely sampled concentration data to pharmacokinetic models that are sometimes complex. In some cases, only a single trough concentration can be practically collected due to the busy nature of many outpatient clinics. Successful TDM, therefore, requires that a team comprising a physician, pharmacist, nurse, phlebotomist, and laboratory professional all work closely together to coordinate and perform this complex monitoring process correctly (1). Each step in this complex process affords the possibility of error, and error is always inevitable. Controlling error in the total testing process is tantamount to TDM success.Laboratory accreditation and proficiency testing programs, along with innovations in laboratory technology, have done a …