Population pharmacokinetic analysis has become a key tool for Clinical Pharmacology experts when working with data from human subjects. In the recent past, new drug registrations utilized pharmacokinetic information from healthy volunteers, in whom intensive PK sampling could be performed. In an effort to examine possible dosage adjustments for patients or other subgroups (e.g. elderly, children, individuals with compromised liver function, etc.) population pharmacokinetic techniques were developed. Clinical researchers began to utilize these techniques to assist in therapeutic drug monitoring and during the drug development process. Population pharmacokinetic techniques are able to accommodate sparse blood sampling designs in clinical settings common to therapeutic treatment and large Phase 3 clinical trials. Further development of population pharmacokinetic techniques have focused on trial simulation and optimization as well as supporting dosage recommendations for target patient populations in the absence of dedicated clinical studies. Although many of these applications are late in the drug development effort, the principles and techniques are also applicable in early drug development when making the transition from nonclinical studies to ﬁrst-in-human clinical trials.
Population pharmacokinetics is based on the principle that the concentration-time proﬁle for each subject can be described with a mathematical model. Systemic drug concentrations (C) are a function time (t) and a set of PK parameters (q) plus residual error (e) as shown in Equation 1.