Physiologically Based Pharmacokinetic (PBPK) Modeling of Antidepressants: A Scoping Review of Existing Models, Applications, and Software Tools

Physiologically based pharmacokinetic models are a valuable tool for simulating antidepressant pharmacokinetics in patient groups that are often underrepresented in clinical trials. Clinical data on antidepressant use in vulnerable populations such as geriatric patients or pregnant women remain limited, making safe and personalized treatment challenging. The objective of this review was to systematically evaluate existing physiologically based pharmacokinetic models for antidepressants, their applications, and the modeling software platforms used, in order to identify relevant research gaps and highlight future needs for model development. A scoping review was conducted in accordance with Preferred Reporting Items for Scoping Reviews (PRISMA-ScR) guidelines. Seven electronic databases were systematically searched. Data on the modeled drug, model applications, and software platforms were extracted and evaluated. A total of 60 studies met the inclusion criteria. The availability of physiologically based pharmacokinetic models across antidepressants was heterogeneous. Paroxetine, fluvoxamine, and venlafaxine were most frequently modeled (n = 10 each), whereas few or no models exist for substances such as mirtazapine (n = 1) or milnacipran (n = 0). The main application areas were drug–drug interactions (n = 18), pregnancy (n = 14), and drug-(drug-)gene interactions (n = 13). Pediatric populations and specific ethnic groups were rarely addressed. SimCyp® Simulator was the most used modeling platform, followed by PK-Sim®/Mobi®, GastroPlus®, and R®/RStudio®. Although physiologically based pharmacokinetic models for antidepressants are increasingly available, they focus on a limited number of drugs and applications. Substantial evidence gaps remain, particularly for vulnerable patient populations. Antidepressants are widely used to treat conditions such as depression. However, there are limited clinical data on how these drugs work in vulnerable populations, including older adults, pregnant women, children, and people with different genetic backgrounds. Physiologically based pharmacokinetic models, or as originally stated in themanuscript. PBPK models, are computer-based tools that simulate how a drug moves through the body. These models can help predict how antidepressants behave in groups that are often underrepresented in clinical studies. This review systematically looked at existing PBPK models for antidepressants, the ways they have been used, and the software platforms employed to create them. Sixty studies were included. Most models focused on the antidepressants paroxetine, fluvoxamine, and venlafaxine, while other drugs such as mirtazapine or milnacipran had very few or no models. The main applications of these models were studying interactions with other drugs, predicting effects during pregnancy, and exploring how genetics affects drug response or drug interactions. Models for children and specific ethnic groups were rare. The most commonly used software was SimCyp® Simulator, followed by PK-Sim®/Mobi®, GastroPlus®, and R®/RStudio®. Overall, PBPK models for antidepressants are increasingly available, but they cover only a limited number of drugs and applications. Large gaps remain, especially for vulnerable patient populations, highlighting the need for future research and model development.