Population pharmacokinetics (pop PK)

Population pharmacokinetics (pop PK) is the study of the sources and correlates of variability in drug concentrations among individuals in the target patient population receiving clinically relevant doses. Rather than intensive sampling in a few volunteers, pop PK analyses sparse samples from many patients using non-linear mixed-effects models (implemented in software such as NONMEM or Monolix) to estimate typical pharmacokinetic parameters, inter-individual and residual variability, and the influence of covariates such as body weight, age, renal function, sex, genotype and concomitant medications.

Pop PK is a cornerstone of model-informed drug development. It supports dose selection and adjustment in special populations (children, the elderly, renal or hepatic impairment), exposure-response analyses for efficacy and safety, justification of dosing in the label, and paediatric extrapolation. The FDA guidance on population pharmacokinetics (2022) and the EMA guideline on reporting pop PK analyses (2007) set expectations for model building, evaluation and reporting.

Pop PK datasets pool pseudonymised individual-level data across trials, sites and countries, often including demographic and genetic covariates that increase identifiability, and are frequently analysed by specialist pharmacometrics consultancies acting as processors. Pooling data collected under different consent documents and national legal frameworks requires a compatibility assessment under Art. 6(4) GDPR or a research legal basis with Art. 89 safeguards, and cross-border sharing of the pooled dataset is an international data transfer to be covered by SCCs or another mechanism.