To discuss TDM and PGx, we need to introduce the concept of pharmacokinetics. Pharmacokinetics is the study of drug disposition in the body, including how and when drugs enter the circulation, how long they remain in the blood, and how they are ultimately eliminated from the body. TDM is the clinical assessment of a drug's pharmacokinetic properties. Physicians and pharmacists need to establish whether or not a given drug is present at a clinically effective concentration in a patient. This ensures that the drug concentration does not reach a toxic level.
The following pages will describe factors determining a drug's disposition in the body. These factors ultimately decide the need for therapeutic drug monitoring.
