25 years of applying the 3Rs principles in safety pharmacology: success stories and future perspectives

Safety pharmacology is a relatively young discipline dedicated to identifying adverse pharmacodynamic effects of new drugs that may impact human safety. Since the publication of the ICH S7A guideline in 2000, the field has made significant efforts in implementing the 3Rs principles—Replacement, Reduction, and Refinement of animal use. This review provides a comprehensive overview of key milestones and innovations that have shaped the application of the 3Rs in safety pharmacology over the past 25 years. Typical examples are the use of non-invasive jacket telemetry for real-time cardiovascular monitoring in conscious freely moving animals and the introduction of the CiPA (Comprehensive in Vitro Proarrhythmia Assessment) paradigm in 2014. The review explores 3Rs-driven advances across core organ systems—cardiovascular, central nervous, and respiratory—as well as supplemental systems including gastrointestinal and renal. Furthermore, it examines the evolving global regulatory landscape and the emergence of new approach methodologies (NAMs), such as artificial intelligence tools and complex microphysiological systems (MPS), and their integration into drug development pipelines. Finally, the review discusses future directions and potential challenges in achieving broader adoption of 3Rs-compliant strategies and NAMs in safety pharmacology.