Experimental biofilm models for pharmacokinetic and pharmacodynamic investigations: bridging <i>in vitro</i> , <i>ex vivo</i> and <i>in vivo</i> systems

Biofilm-associated infections represent a major therapeutic challenge due to reduced antimicrobial susceptibility and the limited predictive value of conventional pharmacokinetic/pharmacodynamic (PK/PD) indices with clinical outcome. A wide spectrum of experimental models has been developed to study biofilms, ranging from simple in vitro assays to ex vivo tissue-derived systems and in vivo infection models. Each category provides distinct advantages: in vitro platforms enable high-throughput compound screening and measurement of biofilm-specific indices such as MBIC and MBEC; ex vivo models preserve host tissue architecture and allow investigation of topical therapies and therapeutic windows; and in vivo systems are indispensable for analysing host-pathogen interactions and systemic PK/PD relationships. No single model is sufficient to replicate clinical biofilm complexity, but combined use and progressive standardization can improve translational value. This review provides a structured overview of available models, their PK/PD readouts and their strengths and limitations, aiming to guide model selection in preclinical biofilm research and antimicrobial development.